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.

A027645 Numerators of poly-Bernoulli numbers B_n^(k) with k=3.

Original entry on oeis.org

1, 1, -11, -1, 1243, -49, -75613, 599, 234671, -803, -4955857, 53443, 921931911863, -449291, -23461249769, 1237447, 917870505450709, -82659252107, -959539811053709101, 145633840717, 20593004175300735901, -12278015226517
Offset: 0

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Crossrefs

Cf. A027646.

Programs

  • Magma
    A027645:= func< n,k | Numerator( (&+[(-1)^(j+n)*Factorial(j)*StirlingSecond(n, j)/(j+1)^k: j in [0..n]]) ) >;
    [A027645(n,3): n in [0..30]]; // G. C. Greubel, Aug 02 2022
    
  • Maple
    a:= (n, k)-> numer((-1)^n*add((-1)^m*m!*Stirling2(n, m)/(m+1)^k, m=0..n)):
    seq(a(n, 3), n = 0..30);
  • Mathematica
    With[{k=3}, Table[Sum[(-1)^(n+j)*j!*StirlingS2[n,j]*(j+1)^(-k), {j,0,n}], {n, 0, 40}]]//Numerator (* G. C. Greubel, Aug 02 2022 *)
  • SageMath
    def A027645(n,k): return numerator( sum((-1)^(n+j)*factorial(j)*stirling_number2(n,j)/(j+1)^k for j in (0..n)) )
    [A027645(n,3) for n in (0..30)] # G. C. Greubel, Aug 02 2022

Formula

a(n) = numerator of Sum_{j=0..n} (-1)^(n+j) * j! * Stirling2(n, j) * (j+1)^(-k), for k = 3.