OFFSET
0,3
FORMULA
a(n) = (-1)^n * n! * Sum_{k=0..floor(n/3)} binomial(2*k-1,n-3*k)/k!.
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-x^3*(1-x)^2)/(1-x)))
(PARI) a(n) = (-1)^n*n!*sum(k=0, n\3, binomial(2*k-1, n-3*k)/k!);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 14 2024
STATUS
approved