-72860domain: ZAppears in sequencesG.f. A(x) satisfies: 1 = Sum_{n>=0} x^n / (A(x)^2 - x)^(2*n+1) * [ Sum_{k=0..n} C(n,k)^2 * x^k * A(x)^(n-2*k) ]^2.at n=21A258053