OFFSET
0,2
FORMULA
G.f.: A(x) = 1/(1 - 2*x*Sum_{k>=0} (k+1)!*x^k ).
EXAMPLE
A(x) = (1 + 2*x + 8*x^2 + 36*x^3 + 176*x^4 + 928*x^5 +..) =
1/(1 - 2/1!*x*(1! + 2!*x + 3!*x^2 + 4!*x^3 + 5!*x^4 +..) ).
PROG
(PARI) {a(n)=local(y=2, 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