9593714460domain: NAppears in sequencesExpansion of (1+x^2*C^2)*C^2, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.at n=19A071721Expansion of -(1 - 8*x) / sqrt(1 - 4*x).at n=18A349846