OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} (-1)^(n-k) * (Product_{j=0..k-1} (3*j+2)) * Stirling2(n,k).
a(0) = 1; a(n) = Sum_{k=1..n} (-1)^k * (k/n - 3) * binomial(n,k) * a(n-k).
a(0) = 1; a(n) = 2*a(n-1) + 2*Sum_{k=1..n-1} binomial(n-1,k) * a(n-k).
PROG
(PARI) a(n) = sum(k=0, n, (-1)^(n-k)*prod(j=0, k-1, 3*j+2)*stirling(n, k, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 15 2023
STATUS
approved