A176720 G.f. satisfies: A(x) = 1 + Sum_{n>=0} 2*x^(n^2)*A(x)^n.

1, 2, 4, 8, 18, 44, 112, 288, 744, 1938, 5104, 13584, 36456, 98468, 267376, 729488, 1999074, 5500412, 15189636, 42084952, 116949848, 325878288, 910333152, 2548892864, 7152113760, 20108587038, 56641227416, 159820928328

Offset: 0

Author

Paul D. Hanna, Apr 25 2010

Keywords

• nonn

Examples

			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 + ...
		

Crossrefs

Cf. A157134, A176719.

Programs

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)}

Extensions

Edited by Paul D. Hanna, Apr 27 2010