151355847012domain: NAppears in sequencesFine's sequence (or Fine numbers): number of relations of valence >= 1 on an n-set; also number of ordered rooted trees with n nodes having root of even degree.at n=24A000957Expansion of (1-2*x-sqrt(1-4*x))/(x^2 * (1+2*x+sqrt(1-4*x))).at n=21A104629A bisection of A000957.at n=12A138413