A007476 -id:A007476 - cp's OEIS frontend

A362549 Number of partitions of [n] whose blocks can be ordered such that the i-th block (except possibly the last) has at least i elements and no block j > i has an element smaller than the i-th smallest element of block i.

1, 1, 2, 4, 9, 23, 64, 187, 566, 1777, 5820, 19944, 71343, 264719, 1011292, 3953381, 15756609, 63945484, 264384828, 1115246518, 4806957739, 21189601861, 95516470253, 439777682222, 2064164172616, 9853934668051, 47736608806520, 234235866539512, 1162618720397931

Offset: 0

Alois P. Heinz, Apr 24 2023

nonn

			a(0) = 1: (), the empty partition.
a(1) = 1: 1.
a(2) = 2: 12, 1|2.
a(3) = 4: 123, 12|3, 13|2, 1|23.
a(4) = 9: 1234, 123|4, 124|3, 12|34, 134|2, 13|24, 14|23, 1|234, 1|23|4.
a(5) = 23: 12345, 1234|5, 1235|4, 123|45, 1245|3, 124|35, 125|34, 12|345, 12|34|5, 1345|2, 134|25, 135|24, 13|245, 13|24|5, 145|23, 14|235, 14|23|5, 15|234, 1|2345, 1|234|5, 15|23|4, 1|235|4, 1|23|45.
a(6) = 64: 123456, 12345|6, 12346|5, 1234|56, 12356|4, ..., 1|2356|4, 1|235|46, 16|23|45, 1|236|45, 1|23|456.

Alois P. Heinz, Table of n, a(n) for n = 0..888
Wikipedia, Partition of a set

Cf. A000110, A007476, A092920, A210540, A362635, A362637, A362893.

b:= proc(n, t) option remember; `if`(n<=t, 1,
      add(b(j, t+1)*binomial(n-t, j), j=0..n-t))
    end:
a:= n-> b(n, 1):
seq(a(n), n=0..30);

A091187 Triangle read by rows: T(n,k) is the number of ordered trees with n edges and k branches.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 6, 4, 1, 4, 12, 16, 9, 1, 5, 20, 40, 45, 21, 1, 6, 30, 80, 135, 126, 51, 1, 7, 42, 140, 315, 441, 357, 127, 1, 8, 56, 224, 630, 1176, 1428, 1016, 323, 1, 9, 72, 336, 1134, 2646, 4284, 4572, 2907, 835, 1, 10, 90, 480, 1890, 5292, 10710, 15240, 14535, 8350, 2188

Offset: 1

Emeric Deutsch, Feb 23 2004

Row sums are the Catalan numbers A000108. Diagonal entries are the Motzkin numbers A001006.
Equals binomial transform of an infinite lower triangular matrix with A001006 as the main diagonal and the rest zeros. [Gary W. Adamson, Dec 31 2008] [Corrected by Paul Barry, Mar 06 2011]
Reversal of A091869. Diagonal sums are A026418(n+2). [Paul Barry, Mar 06 2011]

			Triangle begins:
  1;
  1, 1;
  1, 2,  2;
  1, 3,  6,   4;
  1, 4, 12,  16,   9;
  1, 5, 20,  40,  45,  21;
  1, 6, 30,  80, 135, 126,  51;
  1, 7, 42, 140, 315, 441, 357, 127;

Michael De Vlieger, Table of n, a(n) for n = 1..11325 (rows 1..150, flattened)
J.-L. Baril, S. Kirgizov, The pure descent statistic on permutations, Preprint, 2016.
J. Riordan, Enumeration of plane trees by branches and endpoints, J. Combinat. Theory, Ser A, 19, 214-222, 1975.
Lin Yang and Shengliang Yang, Protected Branches in Ordered Trees, J. Math. Study (2023) Vol. 56, No. 1, 1-17.

Cf. A001006, A000108.

Cf. A007476. [Gary W. Adamson, Dec 31 2008]

M := n->sum(binomial(n+1,q)*binomial(n+1-q,q-1),q=0..ceil((n+1)/2))/(n+1): T := (n,k)->binomial(n-1,k-1)*M(k-1): seq(seq(T(n,k),k=1..n),n=1..13);

(* m = MotzkinNumber *) m[0] = 1; m[n_] := m[n] = m[n - 1] + Sum[m[k]*m[n - 2 - k], {k, 0, n - 2}]; t[n_, k_] := m[k - 1]*Binomial[n - 1, k - 1]; Table[t[n, k], {n, 1, 11}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jul 10 2013 *)

T(n,k) = M(k-1)*binomial(n-1, k-1), where M(k) = A001006(k) = (Sum_{q=0..ceiling((k+1)/2)} binomial(k+1, q)*binomial(k+1-q, q-1))/(k+1) is a Motzkin number.
G.f.: G = G(t,z) satisfies t*z*G^2 -(1 - z + t*z)*G + 1- z + t*z = 0.
From Paul Barry, Mar 06 2011: (Start)
G.f.: 1/(1-x-xy-x^2y^2/(1-x-xy-x^2y^2/(1-x-xy-x^2y^2/(1-... (continued fraction).
G.f.: (1-x(1+y)-sqrt(1-2x(1+y)+x^2(1+2y-3y^2)))/(2x^2*y^2).
E.g.f.: exp(x(1+y))*Bessel_I(1,2*x*y)/(x*y). (End)

A246118 T(n,k), for n,k >= 1, is the number of partitions of the set [n] into k blocks, where, if the blocks are arranged in order of their minimal element, the odd-indexed blocks are all singletons.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 4, 1, 0, 1, 4, 11, 6, 1, 0, 1, 5, 26, 23, 9, 1, 0, 1, 6, 57, 72, 50, 12, 1, 0, 1, 7, 120, 201, 222, 86, 16, 1, 0, 1, 8, 247, 522, 867, 480, 150, 20, 1, 0, 1, 9, 502, 1291, 3123, 2307, 1080, 230, 25, 1, 0, 1, 10, 1013, 3084, 10660, 10044, 6627, 2000, 355, 30, 1

Offset: 1

Peter Bala, Aug 14 2014

Unsigned matrix inverse of A246117. Analog of the Stirling numbers of the second kind, A048993.
This is the triangle of connection constants between the monomial polynomials x^n and the polynomial sequence [x, x^2, x^2*(x - 1), x^2*(x - 1)^2, x^2*(x - 1)^2*(x - 2), x^2*(x - 1)^2*(x - 2)^2, ...]. An example is given below.
Except for differences in offset, this triangle is the Galton array G(floor(k/2),1) in the notation of Neuwirth with inverse array G(-floor(n/2),1).
Essentially the same as A256161. - Peter Bala, Apr 14 2018
From Peter Bala, Feb 10 2020: (Start)
The sums S(n):= Sum_{k >= 0} k^n*(x^k/k!)^2, n = 2,3,4,..., can be expressed as a linear combination of the sums S(0) and S(1) with polynomial coefficients, namely, S(n) = E(n,x)*S(0) + (1/x)*O(n,x)* S(1,x), where E(n,x) = Sum_{k >= 1} T(n,2*k)*x^(2*k) and O(n,x) = Sum_{k >= 0} T(n,2*k+1)*x^(2*k+1) are the even and odd parts of the n-th row polynomial of this array. This result is the analog of the Dobinski formula Sum_{k >= 0} (k^n)*x^k/k! = exp(x)*Bell(n,x), where Bell(n,x) is the n-th row polynomial of A048993.
For example, for n = 6 we have S(6) = Sum_{k >= 1} k^6*(x^k/k!)^2 = (x^2 + 11*x^4 + x^6) * Sum_{k >= 0} (x^k/k!)^2 + (1/x)*(4*x^3 + 6*x^5) * Sum_{k >= 1} k*(x^k/k!)^2.
Setting x = 1 in the above result gives Sum_{k >= 0} k^n*/k!^2 = A000994(n)*Sum_{k >= 0} 1/k!^2 + A000995(n)*Sum_{k >= 1} k/k!^2. See A086880. (End)

			Triangle begins
n\k| 1    2    3    4    5    6    7    8
1  | 1
2  | 0    1
3  | 0    1    1
4  | 0    1    2    1
5  | 0    1    3    4    1
6  | 0    1    4   11    6    1
7  | 0    1    5   26   23    9    1
8  | 0    1    6   57   72   50   12    1
...
Connection constants: Row 6 = (0, 1, 4, 11, 6, 1) so
x^6 = x^2 + 4*x^2*(x - 1) + 11*x^2*(x - 1)^2 + 6*x^2*(x - 1)^2*(x - 2) + x^2*(x - 1)^2*(x - 2)^2.
Row 5 = [0, 1, 3, 4, 1]. There are 9 set partitions of {1,2,3,4,5} of the type described in the Name section:
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Number of      Set partitions                Count
blocks
= = = = = = = = = = = = = = = = = = = = = = = = = = = = =
2                {1}{2,3,4,5}                   1
3           {1}{2,4,5}{3}, {1}{2,3,5}{4},
            {1}{2,3,4}{5}                       3
4          {1}{2,3}{4}{5}, {1}{2,4}{3}{5},
           {1}{2,5}{3}{4}, {1}{2}{3}{4,5}       4
5          {1}{2}{3}{4}{5}                      1

Yue Cai and Margaret Readdy, Negative q-Stirling numbers, arXiv:1506.03249 [math.CO], 2015.
Emrah Kiliç and Helmut Prodinger, Identities with Squares of Binomial Coefficients: an Elementary and Explicit Approach, Publications de l'Institut Mathématique (Beograd) (N.S.), Vol.99(113) (2016), 243-248. See p. 248.
Erich Neuwirth, Recursively defined combinatorial functions: Extending Galton's board, Tech Report TR 99-05, 1999.
E. Neuwirth, Recursively defined combinatorial functions: Extending Galton's board, Discrete Math. 239 (2001) 33-51.

Cf. A000295 (column 4), A007476 (row sums), A008277, A045618 (column 5), A048993, A246117 (unsigned matrix inverse), A256161, A000994, A000995, A086880.

Flatten[Table[Table[Sum[StirlingS2[j,Floor[k/2]] * StirlingS2[n-j-1,Floor[(k-1)/2]],{j,0,n-1}],{k,1,n}],{n,1,12}]] (* Vaclav Kotesovec, Feb 09 2015 *)

T(n,k) = Sum_{i = 0..n-1} Stirling2(i, floor(k/2))*Stirling2(n-i-1, floor((k - 1)/2)) for n,k >= 1.
Recurrence equation: T(1,1) = 1, T(n,1) = 0 for n >= 2; T(n,k) = 0 for k > n; otherwise T(n,k) = floor(k/2)*T(n-1,k) + T(n-1,k-1).
O.g.f. (with an extra 1): A(z) = 1 + Sum_{k >= 1} (x*z)^k/( ( Product_{i = 1..floor((k-1)/2)} (1 - i*z) ) * ( Product_{i = 1..floor(k/2)} (1 - i*z) ) ) = 1 + x*z + x^2*z^2 + (x^2 + x^3)*z^3 + (x^2 + 2*x^3 + x^4)*z^4 + .... satisfies A(z) = 1 + x*z + x^2*z^2/(1 - z)*A(z/(1 - z)).
k-th column generating function z^k/( ( Product_{i = 1..floor((k-1)/2)} (1 - i*z) ) * ( Product_{i = 1..floor(k/2)} (1 - i*z) ) ).
Recurrence for row polynomials: R(n,x) = x^2*Sum_{k = 0..n-2} binomial(n-2,k)*R(k,x) with initial conditions R(0,x) = 1 and R(1,x) = x. Compare with the recurrence satisfied by the Bell polynomials: Bell(n,x) = x*Sum_{k = 0..n-1} binomial(n-1,k) * Bell(k,x).
Row sums are A007476.

A346050 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

0, 1, 1, 0, 1, 3, 6, 11, 23, 60, 179, 553, 1716, 5415, 17801, 61956, 228391, 882309, 3530322, 14531621, 61454091, 267479778, 1200680113, 5561767211, 26553471186, 130366882251, 656668581417, 3387887246292, 17886582294921, 96603394562849, 533645344137390, 3014295344076655

Offset: 0

Ilya Gutkovskiy, Jul 02 2021

nonn

G. C. Greubel, Table of n, a(n) for n = 0..695

Cf. A000994, A000995, A000996, A000997, A000998, A007476, A210540, A346051, A346052.

nmax = 31; A[] = 0; Do[A[x] = x + x^2 + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[0] = 0; a[1] = a[2] = 1; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]

@CachedFunction
def a(n): # a = A346050
    if (n<3): return (0,1,1)[n]
    else: return sum(binomial(n-3,k)*a(k) for k in range(n-2))
[a(n) for n in range(51)] # G. C. Greubel, Nov 28 2022

a(0) = 0, a(1) = a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A346051 G.f. A(x) satisfies: A(x) = 1 + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

1, 0, 1, 1, 1, 2, 5, 12, 28, 68, 181, 531, 1671, 5491, 18627, 65299, 237880, 903907, 3580619, 14729777, 62639952, 274442521, 1236730244, 5729809348, 27292248240, 133614280479, 671803041553, 3464970976743, 18309428363425, 99010800275743, 547462187824465, 3093329527120022

Offset: 0

Ilya Gutkovskiy, Jul 02 2021

nonn

G. C. Greubel, Table of n, a(n) for n = 0..695

Cf. A000994, A000995, A000996, A000997, A000998.

Cf. A007476, A210540, A346050, A346052.

function a(n)
  if n lt 3 then return (1+(-1)^n)/2;
  else return (&+[Binomial(n-3,j)*a(j): j in [0..n-3]]);
  end if; return a;
end function;
[a(n): n in [0..35]]; // G. C. Greubel, Nov 30 2022

nmax = 31; A[] = 0; Do[A[x] = 1 + x^2 + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[0] = 1; a[1] = 0; a[2] = 1; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]

@CachedFunction
def a(n): # a = A346051
    if (n<3): return (1, 0, 1)[n]
    else: return sum(binomial(n-3, k)*a(k) for k in range(n-2))
[a(n) for n in range(51)] # G. C. Greubel, Nov 30 2022

a(0) = 1, a(1) = 0, a(2) = 1; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A346052 G.f. A(x) satisfies: A(x) = 1 + x + x^3 * A(x/(1 - x)) / (1 - x).

Original entry on oeis.org

1, 1, 0, 1, 2, 3, 5, 11, 29, 80, 222, 630, 1881, 6004, 20420, 72979, 270659, 1035590, 4087205, 16675630, 70440641, 307933393, 1390117953, 6462787357, 30871458702, 151298796000, 760250325004, 3915477534861, 20662363081756, 111662169790416, 617482470676567, 3490973387652861

Offset: 0

Ilya Gutkovskiy, Jul 02 2021

nonn

G. C. Greubel, Table of n, a(n) for n = 0..650

Cf. A000994, A000995, A000996, A000997, A000998, A007476, A210540, A346050, A346051.

function a(n) // a = A346052
  if n lt 3 then return Floor((3-n)/2);
  else return (&+[Binomial(n-3,j)*a(j): j in [0..n-3]]);
  end if; return a;
end function;
[a(n): n in [0..35]]; // G. C. Greubel, Nov 30 2022

nmax = 31; A[] = 0; Do[A[x] = 1 + x + x^3 A[x/(1 - x)]/(1 - x) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[0] = a[1] = 1; a[2] = 0; a[n_] := a[n] = Sum[Binomial[n - 3, k] a[k], {k, 0, n - 3}]; Table[a[n], {n, 0, 31}]

@CachedFunction
def a(n): # a = A346052
    if (n<3): return (1, 1, 0)[n]
    else: return sum(binomial(n-3, k)*a(k) for k in range(n-2))
[a(n) for n in range(51)] # G. C. Greubel, Nov 30 2022

a(0) = a(1) = 1, a(2) = 0; a(n) = Sum_{k=0..n-3} binomial(n-3,k) * a(k).

A351438 G.f. A(x) satisfies: A(x) = 1 + x + x^2 * A(x/(1 - x)) / (1 - x)^3.

Original entry on oeis.org

1, 1, 1, 4, 11, 29, 85, 281, 1003, 3764, 14811, 61327, 267153, 1219497, 5807473, 28763988, 147898511, 788330533, 4349414397, 24799271517, 145904796179, 884577652276, 5519858796807, 35415056743815, 233393746525705, 1578437838849645, 10945142365689985, 77752626344174676

Offset: 0

Ilya Gutkovskiy, Feb 11 2022

nonn

Cf. A007476, A045501, A351437.

nmax = 27; A[] = 0; Do[A[x] = 1 + x + x^2 A[x/(1 - x)]/(1 - x)^3 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
a[0] = a[1] = 1; a[n_] := a[n] = Sum[Binomial[n, k + 2] a[k], {k, 0, n - 2}]; Table[a[n], {n, 0, 27}]

a(0) = a(1) = 1; a(n) = Sum_{k=0..n-2} binomial(n,k+2) * a(k).

A208891 Pascal's triangle matrix augmented with a right border of 1's.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 3, 1, 1, 1, 4, 6, 4, 1, 1, 1, 5, 10, 10, 5, 1, 1, 1, 6, 15, 20, 15, 6, 1, 1, 1, 7, 21, 35, 35, 21, 7, 1, 1, 1, 8, 28, 56, 70, 56, 28, 8, 1, 1, 1, 9, 36, 84, 126, 126, 84, 36, 9, 1, 1, 1, 10, 45, 120, 210, 252, 210, 120, 45

Offset: 0

Gary W. Adamson, Mar 03 2012

The eigensequence of this triangle starts as 1, 2, 4, 9, 23, 65,... (cf. A007476).

The flattened sequence differs from A135225 only by an additional leading 1.

			First few rows of the triangle =
1;
1, 1;
1, 1, 1;
1, 2, 1, 1;
1, 3, 3, 1, 1;
1, 4, 6, 4, 1, 1;
1, 5, 10, 10, 5, 1, 1;
1, 6, 15, 20, 15, 6, 1, 1;
1, 7, 21, 35, 35, 21, 7, 1, 1;
1, 8, 28, 56, 70, 56, 28, 8, 1, 1;
1, 9, 36, 84, 126, 126, 84, 36, 9, 1, 1;
1, 10, 45, 120, 210, 252, 210, 120, 45, 10, 1, 1;
...

Cf. A007318, A007476

208891 := proc(n,k)
    if n <0 or k<0 or k>n then
        0;
    elif n = k then
        1 ;
    else
        binomial(n-1,k) ;
    end if;
end proc:
seq(seq(A208891(n,k),k=0..n),n=0..12) ; # R. J. Mathar, Jul 19 2024

T(n,n)=1. T(n,k) = A007318(n-1,k) for k

A256161 Triangle of allowable Stirling numbers of the second kind a(n,k).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 4, 1, 1, 4, 11, 6, 1, 1, 5, 26, 23, 9, 1, 1, 6, 57, 72, 50, 12, 1, 1, 7, 120, 201, 222, 86, 16, 1, 1, 8, 247, 522, 867, 480, 150, 20, 1, 1, 9, 502, 1291, 3123, 2307, 1080, 230, 25, 1, 1, 10, 1013, 3084, 10660, 10044, 6627, 2000, 355, 30, 1

Offset: 1

Margaret A. Readdy, Mar 16 2015

Row sums = A007476 starting (1, 2, 4, 9, 23, 65, 199, 654, 2296, 8569, ...).

a(n,k) counts restricted growth words of length n in the letters {1, ..., k} where every even entry appears exactly once.

			a(4,1) = 1 via 1111;
a(4,2) = 3 via 1211, 1121, 1112;
a(4,3) = 4 via 1213, 1231, 1233, 1123;
a(4,4) = 1 via 1234.
Triangle starts:
  1;
  1,  1;
  1,  2,  1;
  1,  3,  4,  1;
  1,  4, 11,  6,  1;
  ...

Yue Cai and Margaret Readdy, Negative q-Stirling numbers, arXiv:1506.03249 [math.CO], 2015.

Cf. A007476 (row sums), A246118 (essentially the same triangle).

a[, 1] = a[n, n_] = 1;
a[n_, k_] := a[n, k] = a[n-1, k-1] + Ceiling[k/2] a[n-1, k];
Table[a[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Dec 15 2018 *)

a(n,k) = a(n-1,k-1) + ceiling(k/2)*a(n-1,k) for n >= 1 and 1 <= k <= n with boundary conditions a(n,0) = KroneckerDelta[n,0].
a(n,2) = n-1.
a(n,n-1) = floor(n/2)*ceiling(n/2).

A332398 Number of set partitions of [n] where all prime-indexed blocks are singletons.

Original entry on oeis.org

1, 1, 2, 4, 8, 17, 40, 105, 304, 958, 3255, 11851, 46096, 191648, 854551, 4101826, 21213282, 117747119, 695773801, 4332490151, 28149712546, 189300600481, 1309755334070, 9286984108299, 67327505784439, 498502290046850, 3769028024302567, 29115361551715499

Offset: 0

Alois P. Heinz, Feb 10 2020

nonn

			a(2) = 2: 12, 1|2.
a(3) = 4: 123, 12|3, 13|2, 1|2|3.
a(4) = 8: 1234, 123|4, 124|3, 12|3|4, 134|2, 13|2|4, 14|2|3, 1|2|3|4.
a(5) = 17: 12345, 1234|5, 1235|4, 123|4|5, 1245|3, 124|3|5, 125|3|4, 12|3|4|5, 1345|2, 134|2|5, 135|2|4, 13|2|4|5, 145|2|3, 14|2|3|5, 15|2|3|4, 1|2|3|45, 1|2|3|4|5.

Alois P. Heinz, Table of n, a(n) for n = 0..605
Wikipedia, Partition of a set

Cf. A000040, A000110, A007476, A332248.

b:= proc(n, m) option remember; `if`(n=0, 1, add(`if`(j<=m
       and isprime(j), 0, b(n-1, max(j, m))), j=1..m+1))
    end:
a:= n-> b(n, 0):
seq(a(n), n=0..32);
# second Maple program:
b:= proc(n, i) option remember; `if`(n=0, 1, add(b(n-j, i+1)*
       binomial(n-1, j-1), j=1..`if`(isprime(i+1), 1, n)))
    end:
a:= n-> b(n, 0):
seq(a(n), n=0..32);

b[n_, i_] := b[n, i] = If[n == 0, 1, Sum[b[n-j, i+1] Binomial[n-1, j-1], {j, 1, If[PrimeQ[i+1], 1, n]}]];
a[n_] := b[n, 0];
a /@ Range[0, 32] (* Jean-François Alcover, May 07 2020, after 2nd Maple program *)

Previous Showing 11-20 of 29 results. Next

cp's OEIS Frontend

A362549 Number of partitions of [n] whose blocks can be ordered such that the i-th block (except possibly the last) has at least i elements and no block j > i has an element smaller than the i-th smallest element of block i.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Maple

A091187 Triangle read by rows: T(n,k) is the number of ordered trees with n edges and k branches.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Maple

Mathematica

Formula

A246118 T(n,k), for n,k >= 1, is the number of partitions of the set [n] into k blocks, where, if the blocks are arranged in order of their minimal element, the odd-indexed blocks are all singletons.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Mathematica

Formula

A346050 G.f. A(x) satisfies: A(x) = x + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica

SageMath

Formula

A346051 G.f. A(x) satisfies: A(x) = 1 + x^2 + x^3 * A(x/(1 - x)) / (1 - x).

Views

Author

Keywords

Links

Crossrefs

Programs

Magma

Mathematica

SageMath

Formula

A346052 G.f. A(x) satisfies: A(x) = 1 + x + x^3 * A(x/(1 - x)) / (1 - x).

Views

Author

Keywords

Links

Crossrefs

Programs

Magma

Mathematica

SageMath

Formula

A351438 G.f. A(x) satisfies: A(x) = 1 + x + x^2 * A(x/(1 - x)) / (1 - x)^3.

Views

Author

Keywords

Crossrefs

Programs

Mathematica

Formula

A208891 Pascal's triangle matrix augmented with a right border of 1's.

Views

Author

Keywords

Comments

Examples

Crossrefs