22247635905domain: NAppears in sequencesExpansion of g.f. A(x) satisfying A(x)^2 = A(x^2) * (1 - x*C(x)) * (1 - x*C(x^2)) / (1 - 4*x) where C(x) = 1 + x*C(x)^2 is the Catalan function (A000108).at n=19A370540