OFFSET
0,2
EXAMPLE
G.f.: A(x) = 1 + 2*x + 4*x^2 + 8*x^3 + 18*x^4 + 44*x^5 + 112*x^6 +...
A(x) = 1 + 2*x*A(x) + 2*x^4*A(x)^2 + 2*x^9*A(x)^3 + 2*x^16*A(x)^4 + ...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=1+sum(m=1, n, 2*(A+x*O(x^n))^m*x^(m^2))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Apr 25 2010
EXTENSIONS
Edited by Paul D. Hanna, Apr 27 2010
STATUS
approved