OFFSET
0,2
FORMULA
G.f.: A(x) = 1/(1-x)/[Sum_{n>=0} (-1)^n*n!*x^n].
EXAMPLE
A(x) = 1 + 2*x + x^2 + 4*x^3 - 9*x^4 + 62*x^5 - 399*x^6 +-...
= 1/(1-x)/(1 - x + 2*x^2 - 6*x^3 + 24*x^4 - 120*x^5 +-...)
PROG
(PARI) a(n)=polcoeff(1/((1-x)*sum(k=0, n, (-1)^k*k!*x^k)+x*O(x^n)), n)
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Mar 09 2006
STATUS
approved