OFFSET
0,2
PROG
(PARI) {a(n)=local(A, F=(1+x)^3, d=3, G=x, H=1+x, S=ceil(log(n+1)/log(d+1))); for(i=0, n, G=x*subst(F, x, G+x*O(x^n))); for(i=0, S, H=subst(H, x, x*G^d+x*O(x^n))*G/x); A=(x*H-y*subst(H, x, x*y^d +x*O(x^n)))/(x*subst(F, x, y)-y); polcoeff(polcoeff(A, n, x), n, y)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 17 2006
STATUS
approved