Secondary structures, plane trees and Motzkin numbers
نویسندگان
چکیده
A bijective correspondence is established between secondary structures of a given rank and size and plane trees satisfying certain additional conditions. The correspondence is then used to obtain new combinatorial interpretations of Motzkin numbers in terms of plane trees and Dyck paths.
منابع مشابه
Trees Associated with the Motzkin Numbers
We consider plane rooted trees on n+1 vertices without branching points on odd levels. The number of such trees in equal to the Motzkin number M n. We give a bijective proof of this statement. 1. Let P n be the set of all plane rooted trees on n+1 unlabeled vertices with edges oriented from the root (see 1]). We say that a vertex v in a tree T 2 P n is a branching point if at least two edges in...
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