3534526380

Appears in sequences

• a(n) = (1/(4n-1))*C(4n,2n).at n=10A024491
• Dirichlet convolution of Catalan numbers (1,2,5,14...) with themselves.at n=18A034717
• Expansion of (1 + x*C)*C, where C = (1 - (1 - 4*x)^(1/2))/(2*x) is the g.f. for Catalan numbers, A000108.at n=19A068875
• The number of boundary twigs for complete binary twigs. A twig is a vertex with one edge on the boundary and only one other descendant.at n=18A228403
• Number of rooted asymmetrical polyenoids of type U_n* having n edges.at n=19A262543
• a(-1)=-1; a(n) = 2*A000108(n) for n >= 0.at n=20A284016