OFFSET
0,3
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 6*x^3 + 26*x^4 + 164*x^5 +...
where
A(x) = 1 + x*A(x) + x^2*A(x)*A(2*x) + x^3*A(x)*A(2*x)*A(4*x) +...
PROG
(PARI) {a(n, r=1)=local(A=1+x); for(i=1, n, A=1+sum(m=1, n, r^m*x^m*prod(k=0, m-1, subst(A, x, 2^k*x+x*O(x^n))))); polcoeff(A, n)}
for(n=0, 20, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 19 2010
STATUS
approved