OFFSET
0,3
FORMULA
G.f.: Sum_{k>=0} (-x)^k / (1 - 3*k*x)^(k+1).
a(n) = Sum_{k=0..n} (-1)^k * (3*k)^(n-k) * binomial(n,k).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-x*exp(3*x))))
(PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=0, N, (-x)^k/(1-3*k*x)^(k+1)))
(PARI) a(n) = sum(k=0, n, (-1)^k*(3*k)^(n-k)*binomial(n, k));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 29 2022
STATUS
approved