2579248980domain: NAppears in sequencesNumber of unrooted triangulations with reflection symmetry of a disk with one internal node and n+3 nodes on the boundary.at n=35A005508Expansion 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=18A071721