A088956 -id:A088956 - cp's OEIS frontend

A215534 Matrix inverse of triangle A088956.

1, -1, 1, -1, -2, 1, -4, -3, -3, 1, -27, -16, -6, -4, 1, -256, -135, -40, -10, -5, 1, -3125, -1536, -405, -80, -15, -6, 1, -46656, -21875, -5376, -945, -140, -21, -7, 1, -823543, -373248, -87500, -14336, -1890, -224, -28, -8, 1, -16777216, -7411887, -1679616, -262500, -32256, -3402, -336, -36, -9, 1

Offset: 0

Peter Bala, Sep 11 2012

For commuting lower unitriangular matrices A and B, we define A raised to the matrix power B, denoted A^^B, to be the matrix Exp(B*log(A)). Here Exp is the matrix exponential and the matrix logarithm Log(A) is defined as sum {n >= 1} (-1)^(n+1)*(A-1)^n/n. This triangle, call it M, is related to Pascal's triangle P by M^^M = P^(-1). Also M = P^(-1)^^A088956.

			Triangle begins
.n\k.|......0......1.....2......3......4......5......6
= = = = = = = = = = = = = = = = = = = = = = = = = = = =
..0..|......1
..1..|.....-1......1
..2..|.....-1.....-2.....1
..3..|.....-4.....-3....-3......1
..4..|....-27....-16....-6.....-4......1
..5..|...-256...-135...-40....-10.....-5......1
..6..|..-3125..-1536..-405....-80....-15.....-6......1
...

T. Copeland, Composition, Conjugation, and the Umbral Calculus-Part I, 2021.
Eric Weisstein's World of Mathematics, Abel Polynomial.

Cf. A000169, A007318, A088956.

(* The function RiordanArray is defined in A256893. *)
rows = 10;
R = RiordanArray[-#/ProductLog[-#]&, #&, rows, True];
R // Flatten (* Jean-François Alcover, Jul 20 2019 *)

T(n,k) = -binomial(n,k)*(n-k-1)^(n-k-1) for n,k >= 0.
E.g.f.: (x/T(x))*exp(t*x) = exp(-T(x))*exp(t*x) = 1 + (-1 + t)*x + (-1 - 2*t + t^2)*x^2/2! + ...., where T(x) := sum {n >= 0} n^(n-1) *x^n/n! denotes the tree function of A000169. The triangle is the exponential Riordan array [x/T(x),x] belonging to the exponential Appell group.
Let A(n,x) = x*(x+n)^(n-1) be an Abel polynomial. This is the triangle of connection constants expressing A(n,x) as a linear combination of the basis polynomials A(k,x+1), 0 <= k <= n. For example, A(4,x) = -27*A(0,x+1) - 16*A(1,x+1) - 6*A(2,x+1) - 4*A(3,x+1) + A(4,x+1) giving row 4 as [-27,-16,-6,-4,1].

A001858 Number of forests of trees on n labeled nodes.

Original entry on oeis.org

1, 1, 2, 7, 38, 291, 2932, 36961, 561948, 10026505, 205608536, 4767440679, 123373203208, 3525630110107, 110284283006640, 3748357699560961, 137557910094840848, 5421179050350334929, 228359487335194570528, 10239206473040881277575, 486909744862576654283616

Offset: 0

N. J. A. Sloane and Simon Plouffe

The number of integer lattice points in the permutation polytope of {1,2,...,n}. - Max Alekseyev, Jan 26 2010
Equals the number of score sequences for a tournament on n vertices. See Prop. 7 of the article by Bartels et al., or Example 3.1 in the article by Stanley. - David Radcliffe, Aug 02 2022
Number of labeled acyclic graphs on n vertices. The unlabeled version is A005195. The covering case is A105784, connected A000272. - Gus Wiseman, Apr 29 2024

			From _Gus Wiseman_, Apr 29 2024: (Start)
Edge-sets of the a(4) = 38 forests:
  {}  {12}  {12,13}  {12,13,14}
      {13}  {12,14}  {12,13,24}
      {14}  {12,23}  {12,13,34}
      {23}  {12,24}  {12,14,23}
      {24}  {12,34}  {12,14,34}
      {34}  {13,14}  {12,23,24}
            {13,23}  {12,23,34}
            {13,24}  {12,24,34}
            {13,34}  {13,14,23}
            {14,23}  {13,14,24}
            {14,24}  {13,23,24}
            {14,34}  {13,23,34}
            {23,24}  {13,24,34}
            {23,34}  {14,23,24}
            {24,34}  {14,23,34}
                     {14,24,34}
(End)

B. Bollobas, Modern Graph Theory, Springer, 1998, p. 290.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Alois P. Heinz, Table of n, a(n) for n = 0..388 (first 101 terms from T. D. Noe)
J. E. Bartels, J. Mount, and D. J. A. Welsh, The polytope of win vectors. Annals of Combinatorics 1, 1-15 (1997). https://doi.org/10.1007/BF02558460
David Callan, A Combinatorial Derivation of the Number of Labeled Forests, J. Integer Seqs., Vol. 6, 2003.
Huantian Cao, AutoGF: An Automated System to Calculate Coefficients of Generating Functions, thesis, 2002.o
Huantian Cao, AutoGF: An Automated System to Calculate Coefficients of Generating Functions, thesis, 2002.
Huantian Cao, AutoGF: An Automated System to Calculate Coefficients of Generating Functions, thesis, 2002 [Local copy, with permission]
P. Flajolet and R. Sedgewick, Analytic Combinatorics, 2009; see page 132.
Samuele Giraudo, Combalgebraic structures on decorated cliques, Formal Power Series and Algebraic Combinatorics, Séminaire Lotharingien de Combinatoire, 78B.15, 2017, p. 7, arXiv:1709.08416 [math.CO], 2017.
Anton Izosimov, Matrix polynomials, generalized Jacobians, and graphical zonotopes, arXiv:1506.05179 [math.AG], 2015.
Qipeng Kuang, Ondřej Kuželka, Yuanhong Wang, and Yuyi Wang, Bridging Weighted First Order Model Counting and Graph Polynomials, arXiv:2407.11877 [cs.LO], 2024. See pp. 32-33.
Arun P. Mani and Rebecca J. Stones, Congruences for weighted number of labeled forests, INTEGERS 16 (2016). #A17.
J. Pitman, Coalescent Random Forests, J. Combin. Theory, A85 (1999), 165-193.
J. Riordan, Forests of labeled trees, J. Combin. Theory, 5 (1968), 90-103.
J. Riordan, Letter to N. J. A. Sloane, Oct 19 1970
J. Riordan, Letter to N. J. A. Sloane, Nov 10 1975
John Riordan and N. J. A. Sloane, Correspondence, 1974
N. J. A. Sloane, Letter to J. Riordan, Nov. 1970
R. Stanley, Decompositions of rational convex polytopes, Ann. Discrete Math 6.6 (1980): 333-342.
L. Takacs, On the number of distinct forests, SIAM J. Discrete Math., 3 (1990), 574-581.
E. M. Wright, A relationship between two sequences, Proc. London Math. Soc. (3) 17 (1967) 296-304.
Index entries for sequences related to forests

The connected case is A000272, rooted A000169.
The unlabeled version is A005195, connected A000055.
The covering case is A105784, unlabeled A144958.
Row sums of A138464.
For triangles instead of cycles we have A213434, covering A372168.
For a unique cycle we have A372193, covering A372195.
A002807 counts cycles in a complete graph.
A006125 counts simple graphs, unlabeled A000088.
A006129 counts covering graphs, unlabeled A002494.
Cf. A006572, A006573, A088956.
Cf. A053530, A054548, A137916, A263340, A322661, A367863, A372176.

exp(x+x^2+add(n^(n-2)*x^n/n!, n=3..50));
# second Maple program:
a:= proc(n) option remember; `if`(n=0, 1, add(
      binomial(n-1, j-1)*j^(j-2)*a(n-j), j=1..n))
    end:
seq(a(n), n=0..20);  # Alois P. Heinz, Sep 15 2008
# third Maple program:
F:= exp(-LambertW(-x)*(1+LambertW(-x)/2)):
S:= series(F,x,51):
seq(coeff(S,x,j)*j!, j=0..50); # Robert Israel, May 21 2015

nn=20;t=Sum[n^(n-1)x^n/n!,{n,1,nn}];Range[0,nn]!CoefficientList[ Series[Exp[t-t^2/2],{x,0,nn}],x] (* Geoffrey Critzer, Sep 05 2012 *)
nmax = 20; CoefficientList[Series[-LambertW[-x]/(x*E^(LambertW[-x]^2/2)), {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Jul 19 2019 *)

a(n)=if(n<0,0,sum(m=0,n,sum(j=0,m,binomial(m,j)*binomial(n-1,n-m-j)*n^(n-m-j)*(m+j)!/(-2)^j)/m!)) /* Michael Somos, Aug 22 2002 */

E.g.f.: exp( Sum_{n>=1} n^(n-2)*x^n/n! ). This implies (by a theorem of Wright) that a(n) ~ exp(1/2)*n^(n-2). - N. J. A. Sloane, May 12 2008 [Corrected by Philippe Flajolet, Aug 17 2008]
E.g.f.: exp(T - T^2/2), where T = T(x) = Sum_{n>=1} n^(n-1)*x^n/n! is Euler's tree function (see A000169). - Len Smiley, Dec 12 2001
Shifts 1 place left under the hyperbinomial transform (cf. A088956). - Paul D. Hanna, Nov 03 2003
a(0) = 1, a(n) = Sum_{j=0..n-1} C(n-1,j) (j+1)^(j-1) a(n-1-j) if n>0. - Alois P. Heinz, Sep 15 2008

More terms from Michael Somos, Aug 22 2002

A088957 Hyperbinomial transform of the sequence of 1's.

Original entry on oeis.org

1, 2, 6, 29, 212, 2117, 26830, 412015, 7433032, 154076201, 3608522954, 94238893883, 2715385121740, 85574061070045, 2928110179818478, 108110945014584623, 4284188833355367440, 181370804507130015569, 8169524599872649117330, 390114757072969964280163

Offset: 0

Paul D. Hanna, Oct 26 2003

nonn

See A088956 for the definition of the hyperbinomial transform.
a(n) is the number of partial functions on {1,2,...,n} that are endofunctions with no cycles of length > 1.  The triangle A088956 classifies these functions according to the number of undefined elements in the domain.  The triangle A144289 classifies these functions according to the number of edges in their digraph representation (considering the empty function to have 1 edge).  The triangle A203092 classifies these functions according to the number of connected components. - Geoffrey Critzer, Dec 29 2011
a(n) is the number of rooted subtrees (for a fixed root) in the complete graph on n+1 vertices: a(3) = 29 is the number of rooted subtrees in K_4: 1 of size 1, 3 of size 2, 9 of size 3, and 16 spanning subtrees. - Alex Chin, Jul 25 2013 [corrected by Marko Riedel, Mar 31 2019]
From Gus Wiseman, Jan 28 2024: (Start)
Also the number of labeled loop-graphs on n vertices such that it is possible to choose a different vertex from each edge in exactly one way. For example, the a(3) = 29 uniquely choosable loop-graphs (loops shown as singletons) are:
  {}  {1}  {1,2}  {1,12}   {1,2,13}  {1,12,13}
      {2}  {1,3}  {1,13}   {1,2,23}  {1,12,23}
      {3}  {2,3}  {2,12}   {1,3,12}  {1,13,23}
                  {2,23}   {1,3,23}  {2,12,13}
                  {3,13}   {2,3,12}  {2,12,23}
                  {3,23}   {2,3,13}  {2,13,23}
                  {1,2,3}            {3,12,13}
                                     {3,12,23}
                                     {3,13,23}
(End)

			a(5) = 2117 = 1296 + 625 + 160 + 30 + 5 + 1 = sum of row 5 of triangle A088956.

Alois P. Heinz, Table of n, a(n) for n = 0..387
Marko Riedel et al., Proof of e.g.f. of sequence.

Cf. A088956 (triangle).
Row sums of A144289. - Alois P. Heinz, Jun 01 2009
Cf. A086331, A000169.
Column k=1 of A144303. - Alois P. Heinz, Oct 30 2012
The covering case is A000272, also the case of exactly n edges.
Without the choice condition we have A006125 (shifted left).
The unlabeled version is A087803.
The choosable version is A368927, covering A369140, loopless A133686.
The non-choosable version is A369141, covering A369142, loopless A367867.
Cf. A000081, A000085, A057500, A062740, A137916, A277473, A322661, A367904, A368596, A368597, A368924.

a088957 = sum . a088956_row  -- Reinhard Zumkeller, Jul 07 2013

a:= n-> add((n-j+1)^(n-j-1)*binomial(n,j), j=0..n):
seq(a(n), n=0..20);  # Alois P. Heinz, Oct 30 2012

nn = 16; t = Sum[n^(n - 1) x^n/n!, {n, 1, nn}];
Range[0, nn]! CoefficientList[Series[Exp[x] Exp[t], {x, 0, nn}], x]  (* Geoffrey Critzer, Dec 29 2011 *)
With[{nmax = 50}, CoefficientList[Series[-LambertW[-x]*Exp[x]/x, {x, 0, nmax}], x]*Range[0, nmax]!] (* G. C. Greubel, Nov 14 2017 *)

x='x+O('x^10); Vec(serlaplace(-lambertw(-x)*exp(x)/x)) \\ G. C. Greubel, Nov 14 2017

a(n) = Sum_{k=0..n} (n-k+1)^(n-k-1)*C(n, k).
E.g.f.: A(x) = exp(x+sum(n>=1, n^(n-1)*x^n/n!)).
E.g.f.: -LambertW(-x)*exp(x)/x. - Vladeta Jovovic, Oct 27 2003
a(n) ~ exp(1+exp(-1))*n^(n-1). - Vaclav Kotesovec, Jul 08 2013
Binomial transform of A000272. - Gus Wiseman, Jan 25 2024

A009998 Triangle in which j-th entry in i-th row is (j+1)^(i-j).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 8, 9, 4, 1, 1, 16, 27, 16, 5, 1, 1, 32, 81, 64, 25, 6, 1, 1, 64, 243, 256, 125, 36, 7, 1, 1, 128, 729, 1024, 625, 216, 49, 8, 1, 1, 256, 2187, 4096, 3125, 1296, 343, 64, 9, 1, 1, 512, 6561, 16384, 15625, 7776, 2401, 512, 81, 10, 1

Offset: 0

N. J. A. Sloane

Read as a square array this is the Hilbert transform of triangle A123125 (see A145905 for the definition of this term). For example, the fourth row of A123125 is (0,1,4,1) and the expansion (x + 4*x^2 + x^3)/(1-x)^4 = x + 8*x^2 + 27*x^3 + 64*x^4 + ... generates the entries in the fourth row of this array read as a square. - Peter Bala, Oct 28 2008

			Triangle begins:
  1;
  1,  1;
  1,  2,  1;
  1,  4,  3,  1;
  1,  8,  9,  4,  1;
  1, 16, 27, 16,  5,  1;
  1, 32, 81, 64, 25,  6,  1;
  ...
From _Gus Wiseman_, May 01 2021: (Start)
The rows of the triangle are obtained by reading antidiagonals upward in the following table of A(k,n) = n^k, with offset k = 0, n = 1:
         n=1:     n=2:     n=3:     n=4:     n=5:     n=6:
   k=0:   1        1        1        1        1        1
   k=1:   1        2        3        4        5        6
   k=2:   1        4        9       16       25       36
   k=3:   1        8       27       64      125      216
   k=4:   1       16       81      256      625     1296
   k=5:   1       32      243     1024     3125     7776
   k=6:   1       64      729     4096    15625    46656
   k=7:   1      128     2187    16384    78125   279936
   k=8:   1      256     6561    65536   390625  1679616
   k=9:   1      512    19683   262144  1953125 10077696
  k=10:   1     1024    59049  1048576  9765625 60466176
(End)

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 24.

T. D. Noe, Rows n=0..50 of triangle, flattened
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
Peter Luschny, Figurate number - a very short introduction

Row sums give A026898.
Cf. A088956, A123125, A179927.
Column n = 2 of the array is A000079.
Column n = 3 of the array is A000244.
Row k = 2 of the array is A000290.
Row k = 3 of the array is A000578.
Diagonal n = k of the array is A000312.
Diagonal n = k + 1 of the array is A000169.
Diagonal n = k + 2 of the array is A000272.
The transpose of the array is A009999.
The numbers of divisors of the entries are A343656 (row sums: A343657).
A007318 counts k-sets of elements of {1..n}.
A059481 counts k-multisets of elements of {1..n}.
Cf. A002109, A062319, A066959, A143773, A176029, A204688, A326358, A327527.

a009998 n k = (k + 1) ^ (n - k)
a009998_row n = a009998_tabl !! n
a009998_tabl = map reverse a009999_tabl
-- Reinhard Zumkeller, Feb 02 2014

E := (n,x) -> `if`(n=0,1,x*(1-x)*diff(E(n-1,x),x)+E(n-1,x)*(1+(n-1)*x));
G := (n,x) -> E(n,x)/(1-x)^(n+1);
A009998 := (n,k) -> coeff(series(G(n-k,x),x,18),x,k);
seq(print(seq(A009998(n,k),k=0..n)),n=0..6);
# Peter Luschny, Aug 02 2010

Flatten[Table[(j+1)^(i-j),{i,0,20},{j,0,i}]] (* Harvey P. Dale, Dec 25 2012 *)

T(i,j)=(j+1)^(i-j) \\ Charles R Greathouse IV, Feb 06 2017

T(n,n) = 1; T(n,k) = (k+1)*T(n-1,k) for k=0..n-1. - Reinhard Zumkeller, Feb 02 2014

T(n,m) = (m+1)*Sum_{k=0..n-m}((n+1)^(k-1)*(n-m)^(n-m-k)*(-1)^(n-m-k)*binomial(n-m-1,k-1)). - Vladimir Kruchinin, Sep 12 2015

a(62) corrected to 512 by T. D. Noe, Dec 20 2007

A138464 Triangle read by rows: T(n, k) is the number of forests on n labeled nodes with k edges. T(n, k) for n >= 1 and 0 <= k <= n-1.

Original entry on oeis.org

1, 1, 1, 1, 3, 3, 1, 6, 15, 16, 1, 10, 45, 110, 125, 1, 15, 105, 435, 1080, 1296, 1, 21, 210, 1295, 5250, 13377, 16807, 1, 28, 378, 3220, 18865, 76608, 200704, 262144, 1, 36, 630, 7056, 55755, 320544, 1316574, 3542940, 4782969, 1, 45, 990, 14070, 143325, 1092105, 6258000, 26100000, 72000000, 100000000

Offset: 1

N. J. A. Sloane, May 09 2008

The rows of the triangle give the coefficients of the Ehrhart polynomials of integral Coxeter permutahedra of type A. These polynomials count lattice points in a dilated lattice polytope. For a definition see Ardila et al. (p. 1158), the generating functions of these polynomials for the classical root systems are given in theorem 5.2 (p. 1163). - Peter Luschny, May 01 2021

			Triangle begins:
[1]  1;
[2]  1,  1;
[3]  1,  3,   3;
[4]  1,  6,  15,   16;
[5]  1, 10,  45,  110,  125;
[6]  1, 15, 105,  435, 1080,  1296;
[7]  1, 21, 210, 1295, 5250, 13377, 16807;

Alois P. Heinz, Rows n = 1..141, flattened
Federico Ardila, Matthias Beck, and Jodi McWhirter, The arithmetic of Coxeter permutahedra, Rev. Acad. Colomb. Cienc. Ex. Fis. Nat. 44(173):1152-1166, 2020.
John Riordan and N. J. A. Sloane, Correspondence, 1974

Row sums give A001858. Rightmost diagonal gives A000272. Cf. A136605.
Rows reflected give A105599. - Alois P. Heinz, Oct 28 2011
Cf. A088956.
Lower diagonals give: A083483, A239910, A240681, A240682, A240683, A240684, A240685, A240686, A240687. - Alois P. Heinz, Apr 11 2014
T(2n,n) gives A302112.
For Ehrhart polynomials of integral Coxeter permutahedra of classical type cf. this sequence (type A), A343805 (type B), A343806 (type C), A343807 (type D).

T:= proc(n) option remember; if n=0 then 0 else T(n-1) +n^(n-1) *x^n/n! fi end: TT:= proc(n) option remember; expand(T(n) -T(n)^2/2) end: f:= proc(k) option remember; if k=0 then 1 else unapply(f(k-1)(x) +x^k/k!, x) fi end: A:= proc(n,k) option remember; series(f(k)(TT(n)), x,n+1) end: aa:= (n,k)-> coeff(A(n,k), x,n) *n!: a:= (n,k)-> aa(n,n-k) -aa(n,n-k-1): seq(seq(a(n,k), k=0..n-1), n=1..10);  # Alois P. Heinz, Sep 02 2008
alias(W = LambertW): EhrA := exp(-W(-t*x)/t - W(-t*x)^2/(2*t)):
ser := series(EhrA, x, 12): cx := n -> n!*coeff(ser, x, n):
T := n -> seq(coeff(cx(n), t, k), k=0..n-1):
seq(T(n), n = 1..10); # Peter Luschny, Apr 30 2021

t[0, 0] = 1; t[n_ /; n >= 1, k_] /; (0 <= k <= n-1) := t[n, k] = Sum[(i+1)^(i-1)*Binomial[n-1, i]*t[n-i-1, k-i], {i, 0, k}]; t[, ] = 0; Table[t[n, k], {n, 1, 10}, {k, 0, n-1}] // Flatten (* Jean-François Alcover, Jan 14 2014, after Peter Bala *)
gf := E^(-(ProductLog[-(t x)] (2 + ProductLog[-(t x)]))/(2 t));
ser := Series[gf, {x, 0, 12}]; cx[n_] := n! Coefficient[ser, x, n];
Table[CoefficientList[cx[n], t], {n, 1, 10}] // Flatten  (* Peter Luschny, May 01 2021 *)

From Peter Bala, Aug 14 2012: (Start)
T(n+1,k) = Sum_{i=0..k} (i+1)^(i-1)*binomial(n,i)*T(n-i,k-i) with T(0,0)=1.
Recurrence equation for row polynomials R(n,t): R(n,t) = Sum_{k=0..n-1} (k+1)^(k-1)*binomial(n-1,k)*t^k*R(n-k-1,t) with R(0,t) = R(1,t) = 1.
The production matrix for the row polynomials of the triangle is obtained from A088956 and starts:
    1    t
    1    1    t
    3    2    1    t
   16    9    3    1    t
  125   64   18    4    1   t
(End)
E.g.f.: exp( Sum_{n >= 1} n^(n-2)*t^(n-1)*x^n/n! ). - Peter Bala, Nov 08 2015
T(n, k) = [t^k] n! [x^n] exp(-W(-t*x)/t - W(-t*x)^2/(2*t)), where W denotes the Lambert function. - Peter Luschny, Apr 30 2021 [Typo corrected after note from Andrew Howroyd, Peter Luschny, Jun 20 2021]

More terms from Alois P. Heinz, Sep 02 2008

A144303 Square array A(n,m), n>=0, m>=0, read by antidiagonals: A(n,m) = n-th number of the m-th iteration of the hyperbinomial transform on the sequence of 1's.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 6, 1, 1, 4, 13, 29, 1, 1, 5, 22, 81, 212, 1, 1, 6, 33, 163, 689, 2117, 1, 1, 7, 46, 281, 1564, 7553, 26830, 1, 1, 8, 61, 441, 2993, 18679, 101961, 412015, 1, 1, 9, 78, 649, 5156, 38705, 268714, 1639529, 7433032, 1, 1, 10, 97, 911, 8257, 71801, 592489, 4538209, 30640257, 154076201, 1

Offset: 0

Alois P. Heinz, Sep 17 2008, revised Oct 30 2012

See A088956 for the definition of the hyperbinomial transform.

A(n,m), n>=0, m>=0, is the number of subtrees of the complete graph K_{n+m} on n+m vertices containing a given, fixed subtree on m vertices. - Alex Chin, Jul 25 2013

			Square array begins:
  1,     1,      1,      1,      1,       1,       1, ...
  1,     2,      3,      4,      5,       6,       7, ...
  1,     6,     13,     22,     33,      46,      61, ...
  1,    29,     81,    163,    281,     441,     649, ...
  1,   212,    689,   1564,   2993,    5156,    8257, ...
  1,  2117,   7553,  18679,  38705,   71801,  123217, ...
  1, 26830, 101961, 268714, 592489, 1166886, 2120545, ...

Alois P. Heinz, Rows n = 0..140, flattened
N. J. A. Sloane, Transforms

Columns m=0-10 give: A000012, A088957, A089461, A089464, A218496, A218497, A218498, A218499, A218500, A218501, A218502.
Rows n=0-2 give: A000012, A000027, A028872.
Main diagonal gives A252766.
Cf. A007318, A088956.

hymtr:= proc(p) proc(n,m) `if`(m=0, p(n), m*add(
           p(k)*binomial(n, k) *(n-k+m)^(n-k-1), k=0..n))
        end end:
A:= hymtr(1):
seq(seq(A(n, d-n), n=0..d), d=0..12);

a[, 0] = 1; a[n, k_] := Sum[k*(n - j + k)^(n - j - 1)*Binomial[n, j], {j, 0, n}]; Table[a[n - k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Jun 24 2013 *)

E.g.f. of column k: exp(x) * (-LambertW(-x)/x)^k.

A(n,k) = Sum_{j=0..n} k * (n-j+k)^(n-j-1) * C(n,j).

A071207 Triangular array T(n,k) read by rows, giving number of rooted trees on the vertex set {1..n+1} where k children of the root have a label smaller than the label of the root.

Original entry on oeis.org

1, 1, 1, 4, 4, 1, 27, 27, 9, 1, 256, 256, 96, 16, 1, 3125, 3125, 1250, 250, 25, 1, 46656, 46656, 19440, 4320, 540, 36, 1, 823543, 823543, 352947, 84035, 12005, 1029, 49, 1, 16777216, 16777216, 7340032, 1835008, 286720, 28672, 1792, 64, 1, 387420489

Offset: 0

Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002

The n-th term of the n-th binomial transform of a sequence {b} is given by {d} where d(n) = sum(k=0,n,T(n,k)*b(k)) and T(n,k)=binomial(n,k)*n^(n-k); such diagonals are related to the hyperbinomial transform (A088956). - Paul D. Hanna, Nov 04 2003
T(n,k) gives the number of divisors of A181555(n) with (n-k) distinct prime factors. See also A001221, A146289, A146290, A181567. - Matthew Vandermast, Oct 31 2010
T(n,k) is the number of partial functions on {1,2,...,n} leaving exactly k elements undefined.  Row sums = A000169. - Geoffrey Critzer, Jan 08 2012
As a triangular matrix, transforms rows into diagonals in the table of coefficients of successive iterations of x/(1-x). - Paul D. Hanna, Jan 19 2014
Also the number of rooted trees on n+1 labeled vertices in which some specified vertex (say, vertex 1) has k children. - Alan Sokal, Jul 22 2022

			1
1     1
4     4     1
27    27    9     1
256   256   96    16    1
3125  3125  1250  250   25    1
46656 46656 19440 4320  540   36    1

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, Proceedings of FPSAC/SFCA 2000 (Moscow), Springer, pp. 146-157.
Alan D. Sokal, A remark on the enumeration of rooted labeled trees, arXiv:1910.14519 [math.CO], 2019 and Discrete Math. 343, 111865 (2020).

Cf. A000169, A000312, A089466, A088956, A166900.

T:= (n, k)-> binomial(n, k)*n^(n-k): seq(seq(T(n, k), k=0..n), n=0..10);

Prepend[Flatten[ Table[Table[Binomial[n, k] n^(n - k), {k, 0, n}], {n, 1, 8}]], 1]  (* Geoffrey Critzer, Jan 08 2012 *)

T(n,k)=if(k<0 || k>n,0,binomial(n,k)*n^(n-k))

/* Transforms rows into diagonals in the iterations of x/(1-x): */
{T(n, k)=local(F=x, M, N, P, m=n); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x/(1-x+x*O(x^(m+2))))); polcoeff(F, c)); N=matrix(m+1, m+1, r, c, F=x; for(i=1, r, F=subst(F, x, x/(1-x+x*O(x^(m+2))))); polcoeff(F, c)); P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, k+1]}
for(n=0, 10, for(k=0, n, print1(T(n, k), ", ")); print("")) \\ Paul D. Hanna, Jan 19 2014

T(n,k) = binomial(n, k)*n^(n-k).

E.g.f.: (-LambertW(-y)/y)^x/(1+LambertW(-y)). - Vladeta Jovovic

Name edited by Alan Sokal, Jul 22 2022

A089466 Inverse hyperbinomial transform of A089467.

Original entry on oeis.org

1, 1, 3, 18, 163, 1950, 28821, 505876, 10270569, 236644092, 6098971555, 173823708696, 5427760272507, 184267682837992, 6757353631762293, 266191329601854000, 11210291102456374801, 502602430218071545104, 23900770928782913595651, 1201581698963550283673632

Offset: 0

Paul D. Hanna, Nov 08 2003

nonn

See A088956 for the definition of the hyperbinomial transform.

a(n) is the number of functions f:{1,2,...,n}->{1,2,...,n} such that the functional digraph contains no cycles of length 2. - Geoffrey Critzer, Mar 21 2012

Vincenzo Librandi, Table of n, a(n) for n = 0..100

Cf. A089467, A088956.

nn=20; t=Sum[n^(n-1)x^n/n!,{n,1,nn}]; a=Log[1/(1-t)]; Range[0,nn]! CoefficientList[Series[Exp[a-t^2/2], {x,0,nn}], x] (* Geoffrey Critzer, Mar 21 2012 *)

a(n)=if(n<0,0,sum(m=0,n,sum(j=0,m,binomial(m,j)*binomial(n,n-m-j)*(n-1)^(n-m-j)*(m+j)!/(-2)^j)/m!))

a(n) = n! * sum(k=0, n\2, (-1/2)^k * n^(n - 2*k) / (k! * (n - 2*k)!)); \\ Daniel Suteu, Jun 19 2018

A089467(n) = Sum_{k=0..n} (n-k+1)^(n-k-1)*C(n, k)*a(k).
a(n) = Sum_{m=0..n} (Sum_{j=0..m} C(m, j)*C(n, n-m-j)*(n-1)^(n-m-j)*(m+j)!/(-2)^j)/m!.
E.g.f.: exp(-(T(x))^2/2)/(1-T(x)), where T(x) is the e.g.f. for A000169. - Geoffrey Critzer, Mar 21 2012
a(n) ~ exp(-1/2) * n^n. - Vaclav Kotesovec, Oct 08 2013
a(n) = n! * Sum_{k=0..floor(n/2)} (-1/2)^k * n^(n - 2*k) / (k! * (n - 2*k)!). - Daniel Suteu, Jun 19 2018

A236961 Triangle, read by rows, that transforms diagonals in the table of coefficients in the successive iterations of g.f. of A236960 such that column 0 equals T(n,0) = n^n.

Original entry on oeis.org

1, 1, 1, 4, 2, 1, 27, 11, 3, 1, 256, 94, 21, 4, 1, 3125, 1076, 217, 34, 5, 1, 46656, 15362, 2910, 412, 50, 6, 1, 823543, 262171, 47598, 6333, 695, 69, 7, 1, 16777216, 5198778, 915221, 116768, 12045, 1082, 91, 8, 1, 387420489, 117368024, 20182962, 2498414, 247151, 20871, 1589, 116, 9, 1, 10000000000

Offset: 0

Paul D. Hanna, Feb 01 2014

			This triangle begins:
1;
1, 1;
4, 2, 1;
27, 11, 3, 1;
256, 94, 21, 4, 1;
3125, 1076, 217, 34, 5, 1;
46656, 15362, 2910, 412, 50, 6, 1;
823543, 262171, 47598, 6333, 695, 69, 7, 1;
16777216, 5198778, 915221, 116768, 12045, 1082, 91, 8, 1;
387420489, 117368024, 20182962, 2498414, 247151, 20871, 1589, 116, 9, 1;
10000000000, 2970653234, 501463686, 60678776, 5824330, 471666, 33761, 2232, 144, 10, 1; ...
in which column 0 equals T(n,0) = n^n.
ILLUSTRATION.
This triangle transforms diagonals in the table of coefficients in the iterations of G(x), the g.f. of A236960, that starts as:
G(x) = x + x^2 + 2*x^3 + 5*x^4 + 16*x^5 + 79*x^6 + 720*x^7 + 10735*x^8 + 211802*x^9 + 4968491*x^10 + 132655760*x^11 + 3943593218*x^12 +...
The table of coefficients in the successive iterations of G(x) begins:
[1,  0,   0,    0,     0,      0,       0,        0,         0, ...];
[1,  1,   2,    5,    16,     79,     720,    10735,    211802, ...];
[1,  2,   6,   21,    84,    410,    2876,    33235,    581074, ...];
[1,  3,  12,   54,   266,   1463,    9740,    90999,   1308954, ...];
[1,  4,  20,  110,   648,   4102,   28932,   248808,   2972926, ...];
[1,  5,  30,  195,  1340,   9705,   75264,   655599,   7059436, ...];
[1,  6,  42,  315,  2476,  20284,  174304,  1610487,  16952240, ...];
[1,  7,  56,  476,  4214,  38605,  366660,  3656975,  39586868, ...];
[1,  8,  72,  684,  6736,  68308,  712984,  7710392,  88021908, ...];
[1,  9,  90,  945, 10248, 114027, 1299696, 15223599, 185218134, ...];
[1, 10, 110, 1265, 14980, 181510, 2245428, 28396003, 369356822, ...]; ...
Then this triangle T transforms the adjacent diagonals in the above table into each other, as illustrated by:
T*[1, 1,  6,  54,  648,  9705, 174304, 3656975,  88021908, ...]
= [1, 2, 12, 110, 1340, 20284, 366660, 7710392, 185218134, ...];
T*[1, 2, 12, 110, 1340, 20284, 366660,  7710392, 185218134, ...]
= [1, 3, 20, 195, 2476, 38605, 712984, 15223599, 369356822, ...];
T*[1, 3, 20, 195, 2476, 38605,  712984, 15223599, 369356822, ...]
= [1, 4, 30, 315, 4214, 68308, 1299696, 28396003, 701068918, ...]; ...
RELATED TRIANGLE.
Compare this triangle to the triangle A088956(n,k) = (n-k+1)^(n-k-1)*C(n,k), that transforms diagonals in the table of coefficients in the iterations of x/(1-x):
1;
1, 1;
3, 2, 1;
16, 9, 3, 1;
125, 64, 18, 4, 1;
1296, 625, 160, 30, 5, 1;
16807, 7776, 1875, 320, 45, 6, 1; ...

Paul D. Hanna, Table of n, a(n) for n = 0..1829 (rows 0..60)

Cf. A236960, A236962, A236963, A236964, A359716, A359717 (row sums).

Cf. variants: A233531, A088956.

/* From Root Series G, Calculate T(n,k) of Triangle: */
{T(n, k) = my(F=x, M, N, P, m=max(n, k)); M=matrix(m+2, m+2, r, c, F=x;
for(i=1, r+c-2, F=subst(F, x, G +x*O(x^(m+2)))); polcoeff(F, c));
N=matrix(m+1, m+1, r, c, M[r, c]);
P=matrix(m+1, m+1, r, c, M[r+1, c]); (P~*N~^-1)[n+1, k+1]}
/* Calculates Root Series G and then Prints ROWS of Triangle: */
{ROWS=12;V=[1,1];print("");print1("Root Sequence: [1, 1, ");
for(i=2,ROWS,V=concat(V,0);G=x*truncate(Ser(V));
for(n=0,#V-1,if(n==#V-1,V[#V]=n^n-T(n,0));for(k=0,n, T(n,k)));print1(V[#V]", "););
print1("...]");print("");print("");print("Triangle begins:");
for(n=0,#V-2,for(k=0,n,print1(T(n,k),", "));print(""))}

A089463 Triangle, read by rows, of coefficients for the third iteration of the hyperbinomial transform.

Original entry on oeis.org

1, 3, 1, 15, 6, 1, 108, 45, 9, 1, 1029, 432, 90, 12, 1, 12288, 5145, 1080, 150, 15, 1, 177147, 73728, 15435, 2160, 225, 18, 1, 3000000, 1240029, 258048, 36015, 3780, 315, 21, 1, 58461513, 24000000, 4960116, 688128, 72030, 6048, 420, 24, 1, 1289945088

Offset: 0

Paul D. Hanna, Nov 05 2003

Equals the matrix cube of A088956 when treated as a lower triangular matrix. The 3rd hyperbinomial transform of a sequence {b} is defined to be the sequence {d} given by d(n) = Sum_{k=0..n} T(n,k)*b(k), where T(n,k) = 3*(n-k+3)^(n-k-1)*C(n,k). Given a table in which the n-th row is the n-th binomial transform of the first row, then the 3rd hyperbinomial transform of any diagonal results in the 3rd diagonal lower in the table.

			Rows begin:
  {1},
  {3,1},
  {15,6,1},
  {108,45,9,1},
  {1029,432,90,12,1},
  {12288,5145,1080,150,15,1},
  {177147,73728,15435,2160,225,18,1},
  {3000000,1240029,258048,36015,3780,315,21,1},..

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened

Cf. A089464(row sums), A089465(diagonal), A089460, A088956.

Flatten[Table[3(n-k+3)^(n-k-1) Binomial[n,k],{n,0,10},{k,0,n}]] (* Harvey P. Dale, Jun 26 2013 *)

for(n=0,10, for(k=0,n, print1(3*(n-k+3)^(n-k-1)*binomial(n,k), ", "))) \\ G. C. Greubel, Nov 17 2017

T(n, k) = 3*(n-k+3)^(n-k-1)*C(n, k).
E.g.f.: exp(x*y)*(-LambertW(-y)/y)^3.
Note: (-LambertW(-y)/y)^3 = Sum_{n>=0} 3*(n+3)^(n-1)*y^n/n!.

cp's OEIS Frontend

A215534 Matrix inverse of triangle A088956.

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A001858 Number of forests of trees on n labeled nodes.

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A088957 Hyperbinomial transform of the sequence of 1's.

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A009998 Triangle in which j-th entry in i-th row is (j+1)^(i-j).

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A138464 Triangle read by rows: T(n, k) is the number of forests on n labeled nodes with k edges. T(n, k) for n >= 1 and 0 <= k <= n-1.

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A144303 Square array A(n,m), n>=0, m>=0, read by antidiagonals: A(n,m) = n-th number of the m-th iteration of the hyperbinomial transform on the sequence of 1's.

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