OFFSET
0,4
EXAMPLE
G.f.: A(x) = 1 + x + x^2/2!^2 + 10*x^3/3!^2 + 17*x^4/4!^2 +...
A(x) = (1 + x)*(1 + x^2/2!^2)*(1 + x^3/3!^2)*(1 + x^4/4!^2)*...
PROG
(PARI) {a(n)=n!^2*polcoeff(prod(k=1, n, 1+x^k/k!^2 +x*O(x^n)), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 04 2011
STATUS
approved