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