cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A102290 Total number of even lists in all sets of lists, cf. A000262.

Original entry on oeis.org

0, 0, 2, 6, 60, 380, 3990, 37002, 450296, 5373720, 76018410, 1096730030, 17814654132, 299645294676, 5511836578430, 105550556136690, 2171244984679920, 46545825736022192, 1059273836225051346, 25100215228045842390, 626204775725372971820, 16239127347086448236460
Offset: 0

Views

Author

Vladeta Jovovic, Feb 19 2005

Keywords

Crossrefs

Programs

  • Magma
    l:= func< n,b | Evaluate(LaguerrePolynomial(n), b) >;
    [0,0]cat[Factorial(n)*(&+[(-1)^(n+j)*l(j,-1): j in [0..n-2]]): n in [2..30]]; // G. C. Greubel, Mar 09 2021
  • Maple
    Gser:=series(x^2*exp(x/(1-x))/(1-x^2),x=0,22):seq(n!*coeff(Gser,x^n),n=1..21); # Emeric Deutsch
    # second Maple program:
    b:= proc(n) option remember; `if`(n=0, [1, 0], add(
          (p-> p+`if`(j::even, [0, p[1]], 0))(b(n-j)*
            binomial(n-1, j-1)*j!), j=1..n))
        end:
    a:= n-> b(n, 0)[2]:
    seq(a(n), n=0..25);  # Alois P. Heinz, May 10 2016
  • Mathematica
    Rest[CoefficientList[Series[x^2/(1-x^2)*E^(x/(1-x)), {x, 0, 20}], x]* Range[0, 20]!] (* Vaclav Kotesovec, Sep 29 2013 *)
    Table[If[n<2, 0, n!*Sum[(-1)^(n-j)*LaguerreL[j, -1], {j,0,n-2}]], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    [0,0]+[factorial(n)*sum((-1)^(n+j)*gen_laguerre(j,0,-1) for j in (0..n-2)) for n in (2..30)] # G. C. Greubel, Mar 09 2021
    

Formula

E.g.f.: x^2/(1-x^2)*exp(x/(1-x)).
Recurrence: (n-2)*a(n) = (n-2)*n*a(n-1) + (n-1)^2*n*a(n-2) - (n-3)*(n-2)*(n-1)*n*a(n-3). - Vaclav Kotesovec, Sep 29 2013
a(n) ~ sqrt(2)/4 * n^(n+1/4)*exp(2*sqrt(n)-n-1/2) * (1 - 41/(48*sqrt(n))). - Vaclav Kotesovec, Sep 29 2013
a(n) = n! * Sum_{j=0..n-2} (-1)^(n+j)*LaguerreL(j, -1) for n>1 with a(0)=a(1)=0. - G. C. Greubel, Mar 09 2021

Extensions

More terms from Emeric Deutsch, Mar 27 2005
a(0)=0 prepended by Alois P. Heinz, May 10 2016

A152151 Riordan array [(1-x)exp(x/(1-x)),x].

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 4, 3, 0, 1, 21, 16, 6, 0, 1, 136, 105, 40, 10, 0, 1, 1045, 816, 315, 80, 15, 0, 1, 9276, 7315, 2856, 735, 140, 21, 0, 1, 93289, 74208, 29260, 7616, 1470, 224, 28, 0, 1, 1047376, 839601, 333936, 87780, 17136, 2646, 336, 36
Offset: 0

Views

Author

Paul Barry, Nov 26 2008

Keywords

Comments

First column is essentially A052852.

Examples

			Triangle begins
1,
0, 1,
1, 0, 1,
4, 3, 0, 1,
21, 16, 6, 0, 1,
136, 105, 40, 10, 0, 1,
1045, 816, 315, 80, 15, 0, 1,
9276, 7315, 2856, 735, 140, 21, 0, 1,
with production matrix which begins
0, 1,
1, 0, 1,
4, 2, 0, 1,
18, 12, 3, 0, 1,
96, 72, 24, 4, 0, 1,
600, 480, 180, 40, 5, 0, 1;
4320, 3600, 1440, 360, 60, 6, 1
with e.g.f. exp(x*t)(t+1/(1-x)^2).
		

A173227 Partial sums of A000262.

Original entry on oeis.org

1, 2, 5, 18, 91, 592, 4643, 42276, 436629, 5033182, 63974273, 888047414, 13358209647, 216334610860, 3751352135263, 69325155322184, 1359759373992105, 28206375825238458, 616839844140642301, 14181213537729200474, 341879141423814854915, 8623032181189674581256
Offset: 0

Views

Author

Jonathan Vos Post, Feb 13 2010

Keywords

Comments

Partial sums of the number of "sets of lists": number of partitions of {1,..,n} into any number of lists, where a list means an ordered subset. The subsequence of primes begins: 2, 5, 4643, 616839844140642301.

Examples

			a(20) = 1 + 1 + 3 + 13 + 73 + 501 + 4051 + 37633 + 394353 + 4596553 + 58941091 + 824073141 + 12470162233 + 202976401213 + 3535017524403 + 65573803186921 + 1290434218669921 + 26846616451246353 + 588633468315403843 + 13564373693588558173 + 327697927886085654441.
		

Crossrefs

Programs

  • Magma
    l:= func< n,b | Evaluate(LaguerrePolynomial(n), b) >;
    [n eq 0 select 1 else 1 + (&+[ Factorial(j)*( l(j,-1) - l(j-1,-1) ): j in [1..n]]): n in [0..25]]; // G. C. Greubel, Mar 09 2021
  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(
           b(n-j)*j!*binomial(n-1, j-1), j=1..n))
        end:
    a:= proc(n) option remember; b(n)+`if`(n>0, a(n-1), 0) end:
    seq(a(n), n=0..25);  # Alois P. Heinz, May 11 2016
  • Mathematica
    With[{m = 25}, CoefficientList[Exp[x/(1-x)] + O[x]^m, x] Range[0, m-1]!// Accumulate] (* Jean-François Alcover, Nov 21 2020 *)
    Table[1 +Sum[j!*(LaguerreL[j, -1] -LaguerreL[j-1, -1]), {j,n}], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    [1 + sum(factorial(j)*(gen_laguerre(j,0,-1) - gen_laguerre(j-1,0,-1)) for j in (1..n)) for n in (0..30)] # G. C. Greubel, Mar 09 2021
    

Formula

From Vaclav Kotesovec, Oct 25 2016: (Start)
a(n) = 2*n*a(n-1) - (n^2 - n + 1)*a(n-2) + (n-2)*(n-1)*a(n-3).
a(n) ~ exp(2*sqrt(n)-n-1/2)*n^(n-1/4)/sqrt(2) * (1 - 5/(48*sqrt(n))).
(End)
a(n) = 1 + Sum_{j=1..n} j!*( LaguerreL(j,-1) - LaguerreL(j-1,-1) ). - G. C. Greubel, Mar 09 2021

A300159 Number of ways of converting one set of lists containing n elements to another set of lists containing n elements by removing the last element from one of the lists and either appending it to an existing list or treating it as a new list.

Original entry on oeis.org

0, 0, 4, 30, 240, 2140, 21300, 235074, 2853760, 37819800, 543445380, 8416452550, 139753069104, 2476581106740, 46648575724660, 930581784937770, 19597766647728000, 434455097953799344, 10112163333554834820, 246539064280189932270, 6282671083849941925360
Offset: 0

Views

Author

Mitchell Keith Bloch, Feb 26 2018

Keywords

Comments

All terms are even.

Examples

			a(0) = 0 since for 0 lists, 0 conversions are possible.
a(1) = 0 since for the 1 set of 1 list of length 1, there exist no possible conversions.
a(2) = 4 since for the 2 sets of 1 list of length 2, there exists only 1 conversion, and for the 1 set of 2 lists of length 1, there exist 2 conversions.
a(3) = 30 since for the 6 sets of 1 list of length 3, there exists 1 conversion, for the 6 sets of 1 list of length 2 and 1 list of length 1, there exist 3 conversions, and for the 1 set of 3 lists of length 1, there exists 6 conversions.
		

Crossrefs

Extends A000262 to count conversions in addition to sets of lists.

Programs

  • Magma
    l:= func< n,b | Evaluate(LaguerrePolynomial(n,1), b) >;
    [0,0,4]cat[Factorial(n)*( 2*l(n-2,-1) - l(n-3,-1) ): n in [3..30]]; // G. C. Greubel, Mar 09 2021
  • Maple
    b:= proc(n, t, c) option remember; `if`(n=0, t^2-c, add(j!*
          binomial(n-1, j-1)*b(n-j, t+1, c+`if`(j=1, 1, 0)), j=1..n))
        end:
    a:= n-> b(n, 0$2):
    seq(a(n), n=0..25);  # Alois P. Heinz, Mar 05 2018
    # second Maple program:
    a:= proc(n) option remember; `if`(n<6, [0$2, 4, 30, 240, 2140][n+1],
         (n*(2*n^2-13*n+16)*a(n-1)-n*(n-1)*(n-3)*(n-4)*a(n-2))/((n-2)*(n-5)))
        end:
    seq(a(n), n=0..25);  # Alois P. Heinz, Mar 05 2018
  • Mathematica
    (* First program *)
    b[n_, t_, c_]:= b[n,t,c]= If[n==0, t^2 -c, Sum[j! Binomial[n-1, j-1]b[n-j,t+1,c + If[j==1, 1, 0]], {j,n}]];
    a[n_]:= b[n, 0, 0];
    a/@ Range[0, 25] (* Jean-François Alcover, Nov 24 2020, after Alois P. Heinz *)
    (* Second program *)
    Table[If[n<2, 0, n!*(2*LaguerreL[n-2,1,-1] -LaguerreL[n-3,1,-1])], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    [0,0,4]+[factorial(n)*(2*gen_laguerre(n-2,1,-1) - gen_laguerre(n-3,0,-1)) for n in (3..30)] # G. C. Greubel, Mar 09 2021
    

Formula

a(n) = Sum_{i=1..p(n)} (n!/(Product_{j=1..n} k(i,j)!) * ((Sum_{j=1..n} k(i,j))^2 - k(i,1))) (where p(n) is the number of partitions A000041 and k(i,j) is the number of partitions of size j in partitioning i).
From Alois P. Heinz, Mar 05 2018: (Start)
E.g.f.: x^2*(2-x)*exp(x/(1-x))/(x-1)^2.
a(n) = (n*(2*n^2-13*n+16)*a(n-1) - n*(n-1)*(n-3)*(n-4)*a(n-2)) / ((n-2)*(n-5)) for n>5. (End)
a(n) ~ n^(n + 3/4) * exp(2*sqrt(n) - n - 1/2) / sqrt(2). - Vaclav Kotesovec, Jun 02 2018
a(n) = n!*( 2*LaguerreL(n-2,1,-1) - LaguerreL(n-3,1,-1) ) for n > 1, with a(0) = a(1) = 0. - G. C. Greubel, Mar 09 2021

Extensions

More terms from Mitchell Keith Bloch, Mar 05 2018

A316666 Number of simple relaxed compacted binary trees of right height at most one with no sequences on level 1 and no final sequences on level 0.

Original entry on oeis.org

1, 0, 1, 3, 15, 87, 597, 4701, 41787, 413691, 4512993, 53779833, 695000919, 9680369943, 144560191149, 2303928046437, 39031251610227, 700394126116851, 13270625547477177, 264748979672169681, 5547121478845459983, 121784530649198053263, 2795749225338111831429, 66981491857058929294653
Offset: 0

Views

Author

Michael Wallner, Jul 10 2018

Keywords

Comments

A relaxed compacted binary tree of size n is a directed acyclic graph consisting of a binary tree with n internal nodes, one leaf, and at most n pointers. It is constructed from a binary tree of size n, where the first leaf in a post-order traversal is kept and all other leaves are replaced by pointers. These links may point to any node that has already been visited by the post-order traversal. It is called simple if for nodes with two pointers both point to the same node. The right height is the maximal number of right-edges (or right children) on all paths from the root to any leaf after deleting all pointers. See the Wallner link.
a(n) is one of two "basis" sequences for sequences of the form a(0)=a, a(1)=b, a(n) = n*a(n-1) + (n-1)*a(n-2), the second basis sequence being A096654 (with 0 appended as a(0)). The sum of these sequences is listed as A000255. - Gary Detlefs, Dec 11 2018

Crossrefs

Cf. A000032, A000246, A001879, A051577, A213527, A288950, A288952, A288953 (subclasses of relaxed compacted binary trees of right height at most one, see the Wallner link).
Cf. A000166, A000255, A000262, A052852, A123023, A130905, A176408, A201203 (variants of simple relaxed compacted binary trees of right height at most one, see the Wallner link).

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( (3*Exp(-x) + x-2)/(1-x)^2 )); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, Dec 12 2018
  • Maple
    aseq := n-> 3*round((n+2)*n!/exp(1))-(n+2)*n!: bseq := n-> (n+2)*n!- 2* round((n+2)*n!/exp(1)): s := (a,b,n)-> a*aseq(n) + b*bseq( n): seq(s(1,0,n),n = 0..20);  # Gary Detlefs, Dec 11 2018
  • Mathematica
    terms = 24;
    CoefficientList[(3E^-z+z-2)/(1-z)^2 + O[z]^terms, z] Range[0, terms-1]! (* Jean-François Alcover, Sep 14 2018 *)
  • PARI
    Vec(serlaplace((3*exp(-x + O(x^25)) + x - 2)/(1 - x)^2)) \\ Andrew Howroyd, Jul 10 2018
    

Formula

E.g.f.: (3*exp(-z)+z-2)/(1-z)^2.
a(n) ~ (3*exp(-1) - 1) * n * n!. - Vaclav Kotesovec, Jul 12 2018
a(n) = 3*round((n+2)*n!/e) - (n+2)*n!. - Gary Detlefs, Dec 11 2018
From Seiichi Manyama, Apr 25 2025: (Start)
a(n) = 3 * A000255(n) - n! - (n+1)!.
a(0) = 1, a(1) = 0; a(n) = n*a(n-1) + (n-1)*a(n-2). (End)

A317096 Expansion of e.g.f. ((1 - x)/(1 - 2*x))*exp(x/(x - 1)).

Original entry on oeis.org

1, 0, 1, 8, 69, 704, 8485, 118824, 1900297, 34191296, 683657001, 15038537480, 360903291661, 9383240195328, 262727926084429, 7881806223689384, 252217461390469905, 8575390623429206144, 308714050531090308817, 11731134397549023854856, 469245396934886909801941, 19708307298664103361642560
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 01 2018

Keywords

Comments

Lah transform of A000166.

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 26);
    Coefficients(R!(Laplace( ((1-x)/(1-2*x))*Exp(x/(x-1)) ))); // G. C. Greubel, Mar 09 2021
  • Maple
    a:=series(exp(x/(x - 1))*(1 - x)/(1 - 2*x), x=0, 22): seq(n!*coeff(a, x, n), n=0..21); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 21; CoefficientList[Series[Exp[x/(x - 1)] (1 - x)/(1 - 2 x), {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[Binomial[n - 1, k - 1] Subfactorial[k] n!/k!, {k, 0, n}], {n, 0, 21}]
    A317096[n_]:= A317096[n]= n!*(LaguerreL[n,1] + Sum[2^(n-j-2)*LaguerreL[j,1], {j,0, n-2}]); Table[A317096[n], {n,0,25}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    def A317096(n): return factorial(n)*( gen_laguerre(n,0,1) + sum(2^(n-j-2)*gen_laguerre(j,0,1) for j in (0..n-2)) )
    [A317096(n) for n in (0..25)] # G. C. Greubel, Mar 09 2021
    

Formula

a(n) = Sum_{k=0..n} binomial(n-1,k-1)*A000166(k)*n!/k!.
a(n) ~ sqrt(Pi) * 2^(n - 1/2) * n^(n + 1/2) / exp(n+1). - Vaclav Kotesovec, Mar 26 2019
a(n) = n!*(LaguarreL(n,1) + Sum_{j=0..n-2} 2^(n-j-2)*LaguerreL(j,1)). - G. C. Greubel, Mar 09 2021

A323770 Expansion of e.g.f. x*(2 - x)*exp(x/(1 - x))/(2*(1 - x)^2).

Original entry on oeis.org

0, 1, 5, 30, 214, 1775, 16791, 178360, 2101100, 27172269, 382566025, 5823044546, 95253119490, 1666020561595, 31019392831259, 612430207741500, 12778091116288216, 280893425932078745, 6487870112636577165, 157066777096248548134, 3976727555939887035950, 105087648979005066820551
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 27 2019

Keywords

Crossrefs

Programs

  • Magma
    [n eq 0 select 0 else (&+[Binomial(n-1,k)*Binomial(k+2,2)* Factorial(n)/Factorial(k+1): k in [0..n-1]]): n in [0..20]]; // G. C. Greubel, Mar 05 2021
  • Maple
    seq(n!*coeff(series(x*(2-x)*exp(x/(1-x))/(2*(1-x)^2),x=0,22),x,n),n=0..21); # Paolo P. Lava, Jan 29 2019
  • Mathematica
    nmax = 21; CoefficientList[Series[x (2 - x) Exp[x/(1 - x)]/(2 (1 - x)^2), {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[Binomial[n - 1, k - 1] Binomial[k + 1, 2] n!/k!, {k, 0, n}], {n, 0, 21}]
  • Sage
    [0]+[sum(binomial(n-1,k)*binomial(k+2,2)*factorial(n)/factorial(k+1) for k in (0..n-1)) for n in [1..20]] # G. C. Greubel, Mar 05 2021
    

Formula

a(n) = Sum_{k=0..n} binomial(n-1,k-1)*A000217(k)*n!/k!.
a(n) ~ n^(n + 3/4) / (2^(3/2) * exp(n - 2*sqrt(n) + 1/2)). - Vaclav Kotesovec, Jan 27 2019
a(n) = n!*Hypergeometric2F2([1-n, 3], [1, 2], -1). - G. C. Greubel, Mar 05 2021

A347340 E.g.f.: exp( exp(exp(x) - 1) - exp(x) ).

Original entry on oeis.org

1, 0, 1, 4, 17, 91, 587, 4327, 35604, 323316, 3210600, 34574453, 400893066, 4975247460, 65755573847, 921535225267, 13643496840808, 212688569520955, 3480978391442106, 59657975022473437, 1068151956803180295, 19937983367649562025, 387243759600707804811, 7812456801157894913964
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 27 2021

Keywords

Comments

Exponential transform of A058692.
Stirling transform of A000296.

Crossrefs

Programs

  • Maple
    g:= proc(n) option remember; `if`(n=0, 1,
          add(g(n-j)*binomial(n-1, j-1), j=2..n))
        end:
    b:= proc(n, m) option remember; `if`(n=0,
          g(m), m*b(n-1, m)+b(n-1, m+1))
        end:
    a:= n-> b(n, 0):
    seq(a(n), n=0..23);  # Alois P. Heinz, Aug 27 2021
    # second Maple program:
    b:= proc(n, t) option remember; `if`(n=0, 1, add(b(n-j, t)*
          `if`(t=0, 1, b(j, 0)-1)*binomial(n-1, j-1), j=1..n))
        end:
    a:= n-> b(n, 1):
    seq(a(n), n=0..23);  # Alois P. Heinz, Sep 02 2021
  • Mathematica
    nmax = 23; CoefficientList[Series[Exp[Exp[Exp[x] - 1] - Exp[x]], {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[Binomial[n - 1, k - 1] (BellB[k] - 1) a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 23}]
  • PARI
    my(x='x+O('x^25)); Vec(serlaplace(exp(exp(exp(x)-1)-exp(x)))) \\ Michel Marcus, Aug 27 2021

Formula

a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1) * (Bell(k) - 1) * a(n-k).
a(n) = Sum_{k=0..n} Stirling2(n,k) * A000296(k).
a(n) = Sum_{k=0..n} binomial(n,k) * A000258(k) * A000587(n-k).

A358631 Irregular table T(n, k), n >= 0, k > 0, read by rows of extended (due to binary expansion of n) Stirling numbers of the first kind.

Original entry on oeis.org

1, 1, 2, 3, 1, 4, 5, 1, 6, 11, 6, 1, 6, 7, 1, 12, 20, 9, 1, 18, 26, 9, 1, 24, 50, 35, 10, 1, 8, 9, 1, 18, 29, 12, 1, 30, 41, 12, 1, 48, 94, 59, 14, 1, 36, 47, 12, 1, 72, 130, 71, 14, 1, 96, 154, 71, 14, 1, 120, 274, 225, 85, 15, 1, 10, 11, 1, 24, 38, 15, 1, 42
Offset: 0

Views

Author

Mikhail Kurkov, Nov 24 2022

Keywords

Comments

Row n length is A000120(n) + 2.

Examples

			Irregular table begins:
    1,   1;
    2,   3,   1;
    4,   5,   1;
    6,  11,   6,  1;
    6,   7,   1;
   12,  20,   9,  1;
   18,  26,   9,  1;
   24,  50,  35, 10,  1;
    8,   9,   1;
   18,  29,  12,  1;
   30,  41,  12,  1;
   48,  94,  59, 14,  1;
   36,  47,  12,  1;
   72, 130,  71, 14,  1;
   96, 154,  71, 14,  1;
  120, 274, 225, 85, 15, 1;
		

Crossrefs

Programs

  • PARI
    b1(n)=if(n>0, my(A=n - 2^logint(n, 2)); if(A>0, logint(A, 2) + 1))
    b2(n)=if(n>0, my(A=b1(3*2^logint(n, 2) - n - 1)); n + if(A>0, 2^(A-1)))
    P(n,k)=if(n==0 || k==1, (n==0 && k<3) + (k==1 && n>0), my(L=logint(n, 2), A=n - 2^L); (hammingweight(A) + 2)*P(A, k-1)*(L - b1(n) + 1) + P(b2(A), k))
    T(n, k)=my(A=hammingweight(n)); if(k<=(A + 2), P(n, A - k + 3))

Formula

T(n, k) = P(n, wt(n) - k + 3) for n >= 0, 0 < k <= wt(n) + 2 where wt(n) = A000120(n).
P(n, 1) = 1 for n > 0 with P(0, 1) = P(0, 2) = 1.
P(n, k) = (A000120(q(n)) + 2)*P(q(n), k-1)*(A290255(n) + 1) + P(s(q(n)), k) for n > 0, k > 1 where q(n) = A053645(n) and where s(n) = n + [A063250(n) > 0]*2^(A063250(n) - 1).
T(2^n - 1, k) = abs(Stirling1(n+2, k)) for n >= 0, k > 0.
Conjectures: (Start)
T(n, 1) = (A000120(n) + 1)!*A347205(n) for n >= 0.
Sum_{k=1..A000120(n) + 2} T(n, k)*(-1)^k = 0 for n >= 0.
Sum_{k=0..2^n - 1} Sum_{j=1..A000120(k) + 2} T(k, j) = 2*A052852(n+1) for n >= 0.
Sum_{i=1..wt(k) + 2} m^(i-1)*T(k, i) = (wt(k) + 1)!*A347205(2^m*(2k+1)) for m >= 0, k >= 0 where wt(n) = A000120(n). (End)

Extensions

Offset corrected by Mikhail Kurkov, Nov 07 2024

A361893 Triangle read by rows. T(n, k) = n! * binomial(n - 1, k - 1) / (n - k)!.

Original entry on oeis.org

1, 0, 1, 0, 2, 2, 0, 3, 12, 6, 0, 4, 36, 72, 24, 0, 5, 80, 360, 480, 120, 0, 6, 150, 1200, 3600, 3600, 720, 0, 7, 252, 3150, 16800, 37800, 30240, 5040, 0, 8, 392, 7056, 58800, 235200, 423360, 282240, 40320, 0, 9, 576, 14112, 169344, 1058400, 3386880, 5080320, 2903040, 362880
Offset: 0

Views

Author

Peter Luschny, Mar 28 2023

Keywords

Examples

			Triangle T(n, k) starts:
  [0] 1;
  [1] 0, 1;
  [2] 0, 2,   2;
  [3] 0, 3,  12,     6;
  [4] 0, 4,  36,    72,     24;
  [5] 0, 5,  80,   360,    480,     120;
  [6] 0, 6, 150,  1200,   3600,    3600,     720;
  [7] 0, 7, 252,  3150,  16800,   37800,   30240,    5040;
  [8] 0, 8, 392,  7056,  58800,  235200,  423360,  282240,   40320;
  [9] 0, 9, 576, 14112, 169344, 1058400, 3386880, 5080320, 2903040, 362880;
		

Crossrefs

Cf. A052852 (row sums), A317365 (alternating row sums), A000142 (main diagonal), A187535 (central column), A062119, A055303, A011379.

Programs

  • Maple
    A361893 := (n, k) -> n!*binomial(n - 1, k - 1)/(n - k)!:
    seq(seq(A361893(n,k), k = 0..n), n = 0..9);
    # Using the egf.:
    egf := 1 + (x*y/(1 - x*y))*exp(y/(1 - x*y)): ser := series(egf, y, 10):
    poly := n -> convert(n!*expand(coeff(ser, y, n)), polynom):
    row := n -> seq(coeff(poly(n), x, k), k = 0..n): seq(print(row(n)), n = 0..6);

Formula

T(n, k) = k! * binomial(n, k) * binomial(n - 1, k - 1).
T(n + 1, k + 1) / (n + 1) = A144084(n, k) = (-1)^(n - k)*A021010(n, k).
T(n, k) = [x^k] n! * ([y^n](1 + (x*y / (1 - x*y)) * exp(y / (1 - x*y)))).
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