OFFSET
0,3
FORMULA
G.f.: Sum_{k>=0} (-2*x)^k / (1 - (k+3)*x)^(k+1).
a(n) = Sum_{k=0..n} (-2)^k * (k+3)^(n-k) * binomial(n,k).
PROG
(PARI) a(n) = sum(k=0, n, (-2)^k*(k+3)^(n-k)*binomial(n, k));
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Dec 03 2023
STATUS
approved