OFFSET
0,3
FORMULA
a(n) = n! * Sum_{k=0..floor(n/2)} (3*k)!/(2*k+1)! * |Stirling1(n-k,k)|/(n-k)!.
PROG
(PARI) a(n) = n!*sum(k=0, n\2, (3*k)!/(2*k+1)!*abs(stirling(n-k, k, 1))/(n-k)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 12 2024
STATUS
approved