OFFSET
0,5
FORMULA
a(n) = n! * Sum_{k=0..floor(n/3)} Stirling2(n-2*k,n-3*k)/(n-2*k)!.
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp((exp(x^3)-1)/x^2)))
(PARI) a(n) = n!*sum(k=0, n\3, stirling(n-2*k, n-3*k, 2)/(n-2*k)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 22 2022
STATUS
approved