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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A271204 Triangle of generalized Stirling numbers of the second kind S(n,k) associated with the generalized Bell numbers A271049(n); S(n,k) = Sum_{j=0..k} (-1)^(k-j)*binomial(k,j)*Gamma((j+2)/3)*Gamma(3*n+j-1)/(Gamma(j)*Gamma(n+(j-1)/3))/(3^(n-1)*k!).

Original entry on oeis.org

1, 2, 1, 40, 50, 14, 1, 2240, 4240, 2200, 440, 36, 1, 246400, 608960, 447200, 141520, 22080, 1760, 68, 1, 44844800, 134780800, 125843200, 53412800, 12015360, 1538320, 114800, 4900, 110, 1, 12197785600, 42767648000, 47935328000, 25213686400, 7308806400, 1268761760, 137790240, 9523920, 416000, 11050, 162, 1
Offset: 0

Views

Author

Karol A. Penson, Apr 01 2016

Keywords

Comments

The n-th row sum gives A271049(n): Sum_{k=0..2*n}S(n,k) = A271049(n)

Examples

			Example: S(n,k) in table form for n=0..4;
1
2,1
40,50,14,1
2240, 4240, 2200, 440, 36, 1
246400, 608960, 447200, 141520, 22080, 1760, 68, 1.
		

Crossrefs

Cf. A271049.

Programs

  • Maple
    S:=proc(n,k) (((-1)^k*(3^(-n))*k/(4*(k!))) *(-12*GAMMA(3*n)*hypergeom([1/3-k/3,2/3-k/3,1-k/3,n+1/3,n+2/3],[1/3,2/3,2/3,4/3],1)/GAMMA(n)+6*(k-1)*GAMMA(4/3)*GAMMA(1+3*n)*hypergeom([2/3-k/3,1-k/3,4/3-k/3,2/3+n,n+1],[2/3,1,4/3,5/3],1)/GAMMA(n+1/3)-(k-2)*(k-1)*GAMMA(5/3)*GAMMA(3*n+2)*hypergeom([1-k/3,4/3-k/3,5/3-k/3,n+1,n+4/3],[4/3,4/3,5/3,2],1)/GAMMA(n+2/3)));end;
    for n from 1 to 6 do seq(round(evalf(S(n,kk))),kk=1..2*n) end do;
    # The above Maple program reproduces the data without the initial value 1.

Formula

Special values of generalized hypergeometric functions of type 5F4, in Maple notation: S(n,k) = (((-1)^k*(3^(-n))*k/(4*(k!))) *(-12*GAMMA(3*n)*hypergeom([1/3-k/3,2/3-k/3,1-k/3,n+1/3,n+2/3],[1/3,2/3,2/3,4/3],1)/GAMMA(n)+6*(k-1)*GAMMA(4/3)*GAMMA(1+3*n)*hypergeom([2/3-k/3,1-k/3,4/3-k/3,2/3+n,n+1],[2/3,1,4/3,5/3],1)/GAMMA(n+1/3)-(k-2)*(k-1)*GAMMA(5/3)*GAMMA(3*n+2)*hypergeom([1-k/3,4/3-k/3,5/3-k/3,n+1,n+4/3],[4/3,4/3,5/3,2],1)/GAMMA(n+2/3)))

A383874 a(n) = (3*n+1)!*(3*n)!/((2*n)!*((n+1)!)^2).

Original entry on oeis.org

1, 18, 4200, 3175200, 5137292160, 14544244915200, 64008493310361600, 405192226643043840000, 3493057136053143859200000, 39378260464472988708249600000, 562659674639968187756457984000000, 9940535265182157971578474463232000000, 212816707229761791940688046273331200000000
Offset: 0

Views

Author

Karol A. Penson, May 22 2025

Keywords

Crossrefs

Programs

  • Mathematica
    A383874[n_] := (3*n+1)!*(3*n)!/((2*n)!*((n+1)!)^2);
    Array[A383874, 15, 0] (* Paolo Xausa, May 26 2025 *)
  • PARI
    a(n) = (3*n+1)!*(3*n)!/((2*n)!*((n+1)!)^2); \\ Michel Marcus, May 22 2025

Formula

O.g.f.: hypergeom([1/3, 2/3, 2/3, 1, 1, 4/3], [1/2, 2, 2], (729*x)/4).
E.g.f.: hypergeom([1/3, 2/3, 2/3, 1, 1, 4/3], [1/2, 2, 2, 1], (729*x)/4).
a(n) = Integral_{x>=0} x^n*W(x)*dx, n>=0, with W(x) = MeijerG([[],[-1/2,1,1]],[[0,-1/3,-1/3,1/3,-2/3],[]],4*x/729)/(81*Pi^(3/2)), where MeijerG is the Meijer G - function. Apparently W(x) cannot be represented by any other simpler functions. W(x) is a positive function on (0,oo), is singular at x = 0 and goes monotonically to zero as x -> oo. Thus a(n) is a positive definite sequence.
W(x) is the solution of the Stieltjes moment problem and it may be non-unique.
a(n) ~ 3^(6*n+2) * n^(2*n - 3/2) / (sqrt(Pi) * 2^(2*n+1) * exp(2*n)). - Vaclav Kotesovec, May 24 2025
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