OFFSET
0,2
FORMULA
a(n) = n! * Sum_{k=0..floor(n/3)} binomial(n+2,n-3*k)/k!.
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp((x/(1-x))^3)/(1-x)^3))
(PARI) a(n) = n!*sum(k=0, n\3, binomial(n+2, n-3*k)/k!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 06 2024
STATUS
approved