OFFSET
0,2
FORMULA
a(n) = (n+1)^2 * n * a(n-1) + 1.
PROG
(PARI) a(n) = (n+1)^2*n!^3*sum(k=0, n, 1/((k+1)^2*k!^3));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jan 05 2024
STATUS
approved