OFFSET
0,4
FORMULA
a(n) = n! * [x^n] n/(n - 1 + exp(n*x)) for n > 0.
MATHEMATICA
a[n_] := Sum[k! * (-1)^k * n^(n - k) * StirlingS2[n, k], {k, 0, n}]; a[0] = 1; Array[a, 20, 0] (* Amiram Eldar, Jun 30 2022 *)
PROG
(PARI) a(n) = sum(k=0, n, k!*(-1)^k*n^(n-k)*stirling(n, k, 2));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 30 2022
STATUS
approved