OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..253
FORMULA
a(n) = Sum_{k=0..n} Stirling1(n,k) * k!^2. - Vaclav Kotesovec, Jul 05 2021
a(n) ~ exp(-1/2) * n!^2. - Vaclav Kotesovec, Jul 05 2021
E.g.f.: Sum_{k>=0} k! * log(1+x)^k. - Seiichi Manyama, Apr 22 2022
MATHEMATICA
Table[Sum[Abs[StirlingS1[n, k]](-1)^(n-k)k!^2, {k, 0, n}], {n, 0, 100}]
Table[Sum[StirlingS1[n, k] * k!^2, {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Jul 05 2021 *)
PROG
(Maxima) makelist(sum(abs(stirling1(n, k))*(-1)^(n-k)*k!^2, k, 0, n), n, 0, 24);
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, k!*log(1+x)^k))) \\ Seiichi Manyama, Apr 22 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Emanuele Munarini, Jul 04 2011
STATUS
approved