253771944529domain: NAppears in sequencesG.f. satisfies: A(x) = (1 + x*A(x)^2)/(1 - x^2).at n=21A143330G.f. satisfies: A(x) = exp( Sum_{n>=1} [A(x)^n + A(x)^-n]*x^n/n ).at n=21A171199