OFFSET
1,2
EXAMPLE
G.f.: A(x) = x + 10*x^2 + 10*x^3 + 5*x^4 + 10*x^5 + 5*x^6 +...
then A(x) = B(B(B(B(B(B(B(B(B(B(x)))))))))) where
B(x) = x + x^2 - 8*x^3 + 104*x^4 - 1619*x^5 + 27437*x^6 +...
is the g.f. of A112121.
PROG
(PARI) {a(n, m=10)=local(F=x+x^2+x*O(x^n), G); if(n<1, 0, for(k=3, n, G=F+x*O(x^k); for(i=1, m-1, G=subst(F, x, G)); F=F-((polcoeff(G, k)-1)\m)*x^k); G=F+x*O(x^n); for(i=1, m-1, G=subst(F, x, G)); return(polcoeff(G, n, x)))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Aug 27 2005
STATUS
approved