OFFSET
0,2
FORMULA
G.f.: A(x) = 1/(1 - (1/20)*x*Sum_{k>=0} (k+5)!*x^k ).
EXAMPLE
A(x) = (1 + 6*x + 72*x^2 + 900*x^3 + 11520*x^4 + 149904*x^5 +..)
= 1/(1 - 6/5!*x*(5! + 6!*x + 7!*x^2 + 8!*x^3 + 9!*x^4 +..) ).
PROG
(PARI) {a(n)=local(y=6, 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