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A027645
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Numerators of poly-Bernoulli numbers B_n^(k) with k=3.
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6
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1, 1, -11, -1, 1243, -49, -75613, 599, 234671, -803, -4955857, 53443, 921931911863, -449291, -23461249769, 1237447, 917870505450709, -82659252107, -959539811053709101, 145633840717, 20593004175300735901, -12278015226517
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OFFSET
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0,3
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LINKS
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Masanobu Kaneko, Poly-Bernoulli numbers, Journal de théorie des nombres de Bordeaux, 9 no. 1 (1997), pp. 221-228.
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FORMULA
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a(n) = numerator of Sum_{j=0..n} (-1)^(n+j) * j! * Stirling2(n, j) * (j+1)^(-k), for k = 3.
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MAPLE
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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);
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MATHEMATICA
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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 *)
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PROG
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(Magma)
A027645:= func< n, k | Numerator( (&+[(-1)^(j+n)*Factorial(j)*StirlingSecond(n, j)/(j+1)^k: j in [0..n]]) ) >;
(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)) )
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CROSSREFS
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KEYWORD
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sign,frac
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AUTHOR
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STATUS
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approved
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