OFFSET
0,3
FORMULA
a(n) = n! * Sum_{j=0..n} Sum_{k=0..j} k! * binomial(j,n-j-k) * Stirling2(j,k)/j!.
PROG
(PARI) a(n) = n!*sum(j=0, n, sum(k=0, j, k!*binomial(j, n-j-k)*stirling(j, k, 2)/j!));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 15 2024
STATUS
approved