254909413218domain: NAppears in sequencesG.f. A(x) satisfies A(x) = (1 + x * A(-x)) / (1 - x * A(x)).at n=21A348957G.f. A(x) satisfies A(x) = ( 1 + 4*x*A(x)/(1 - x*A(x)) )^(1/2).at n=21A372018