a(n) = coefficient of x^(2n) in A(x) such that A(x) = G(x)^2 where G(x) = 1 + Sum_{n>=1} (-1)^n x^(4n^2) (F(x/2)^(2n) + F(-x/2)^(2n)), and F(x) is the g.f. of A357787.

A357803

a(n) = coefficient of x^(2*n) in A(x) such that A(x) = G(x)^2 where G(x) = 1 + Sum_{n>=1} (-1)^n * x^(4*n^2) * (F(x/2)^(2*n) + F(-x/2)^(2*n)), and F(x) is the g.f. of A357787.