OFFSET
0,4
FORMULA
a(n) = n! * Sum_{j=0..floor(n/2)} Sum_{k=0..j} binomial(j,n-2*j-k) * |Stirling1(j,k)|/j!.
PROG
(PARI) a(n) = n!*sum(j=0, n\2, sum(k=0, j, binomial(j, n-2*j-k)*abs(stirling(j, k, 1))/j!));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 13 2024
STATUS
approved