61366

Appears in sequences

• Numbers n such that sigma(2*phi(n)) = 2*sigma(n).at n=27A137733
• G.f.: A(x) = F(x*G(x)^2) where F(x) = G(x*F(x)) = 1 + x*F(x)^3 is the g.f. of A001764 and G(x) = F(x/G(x)) = 1 + x*G(x)^2 is the g.f. of A000108 (Catalan).at n=7A153391
• Number of simple unlabeled graphs on n nodes with exactly 3 connected components that are trees or cycles.at n=15A215983