OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..425
FORMULA
a(n) = n! * Sum_{k=0..floor(n/2)} k^(n - 2*k)/(n - 2*k)!.
a(n) ~ n! / ((1 + LambertW(1/2)) * 2^(n+1) * LambertW(1/2)^n). - Vaclav Kotesovec, Oct 30 2022
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x^2*exp(x))))
(PARI) a(n) = n!*sum(k=0, n\2, k^(n-2*k)/(n-2*k)!);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Oct 30 2022
STATUS
approved