OFFSET
0,6
FORMULA
a(n) = n! * Sum_{k=0..floor(n/4)} Stirling2(n-3*k,n-4*k)/(n-3*k)!.
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp((exp(x^4)-1)/x^3)))
(PARI) a(n) = n!*sum(k=0, n\4, stirling(n-3*k, n-4*k, 2)/(n-3*k)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 22 2022
STATUS
approved