OFFSET
0,2
FORMULA
a(n) = 1/(n+1) * Sum_{k=0..n+1} (-2)^k * 3^(n+1-k) * k^n * binomial(n+1,k).
a(n) = n! * Sum_{k=0..n} (-2)^k * Stirling2(n,k)/(n-k+1)!. - Seiichi Manyama, Nov 07 2024
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(serreverse(x/(3-2*exp(x)))/x))
(PARI) a(n) = sum(k=0, n+1, (-2)^k*3^(n+1-k)*k^n*binomial(n+1, k))/(n+1);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Mar 08 2024
STATUS
approved