OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..270
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 23*x^4 + 106*x^5 + 565*x^6 +...
where
A(x) = 1 + x*(1-x)/(1-2*x) + x^2*(1-x)*(1-2*x)/((1-2*x)*(1-4*x)) + x^3*(1-x)*(1-2*x)*(1-3*x)/((1-2*x)*(1-4*x)*(1-6*x)) +...
PROG
(PARI) {a(n)=polcoeff(sum(m=0, n, x^m*prod(k=1, m, (1-k*x)/(1-(2*k)*x +x*O(x^n)))), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 22 2011
STATUS
approved