OFFSET
0,2
FORMULA
G.f.: A(x) = 1/(1 - (3/2)*x*Sum_{k>=0} (k+2)!*x^k ).
EXAMPLE
A(x) = (1 + 3*x + 18*x^2 + 117*x^3 + 801*x^4 + 5724*x^5 +..)
= 1/(1 - 3/2!*x*(2! + 3!*x + 4!*x^2 + 5!*x^3 + 6!*x^4 +..) ).
PROG
(PARI) {a(n)=local(y=3, x=X+X*O(X^n)); polcoeff(1/(1 - y/(y-1)!*x*sum(k=0, n, (y-1+k)!*x^k)), n, X)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Philippe Deléham and Paul D. Hanna, Oct 26 2005
STATUS
approved