A343579 a(n) = Sum_{k=0..floor(n/2)} |Stirling1(n - k, k)|.
1, 0, 1, 1, 3, 9, 36, 176, 1030, 7039, 55098, 486346, 4780445, 51787405, 613045468, 7873065045, 109021348618, 1619197654575, 25675094145535, 432908683794379, 7733991639921585, 145933532935469016, 2900112108790279902, 60543749629794205640, 1324677739541613767983
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..451
Programs
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Mathematica
Table[Sum[Abs[StirlingS1[n - k, k]], {k, 0, Floor[n/2]}], {n, 0, 30}] (* Vaclav Kotesovec, Apr 09 2022 *) -
PARI
a(n) = sum(k=0, n\2, abs(stirling(n-k, k, 1))); \\ Michel Marcus, Apr 22 2021
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PARI
my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, x^k*prod(j=0, k-1, j+x))) \\ Seiichi Manyama, Apr 08 2022
Formula
a(n) ~ n! / n^2. - Vaclav Kotesovec, Apr 09 2022
Comments