OFFSET
0,5
FORMULA
a(n) = n! * Sum_{j=0..floor(n/3)} Sum_{k=0..j} k! * binomial(j,n-3*j-k) * |Stirling1(j,k)|/j!.
PROG
(PARI) a(n) = n!*sum(j=0, n\3, sum(k=0, j, k!*binomial(j, n-3*j-k)*abs(stirling(j, k, 1))/j!));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 15 2024
STATUS
approved