103020253

Appears in sequences

• Number of nodes of even outdegree (including leaves) in all ordered trees with n edges.at n=15A026641
• a(n) = A026637(n, floor(n/2)).at n=29A026643
• Number of symmetric Dyck paths of semilength n and having no hills (i.e., no peaks at level 1).at n=30A109078
• Number left factors of Dyck paths of length n and having no hills; a hill is a (1,1)-step starting at level 0 and followed by a (1,-1)-step.at n=30A191526