29 citations · 38 across the 8 of their papers we have counts for
8 papers
Potential Polynomials and Motzkin Paths
Yidong Sun
A {\em Motzkin path} of length is a lattice path from to in the plane integer lattice consisting of horizontal-steps , up-s…
Pattern Avoidance in Generalized Non-crossing Trees
Yidong Sun, Zhiping Wang
In this paper, the problem of pattern avoidance in generalized non-crossing trees is studied. The generating functions for generalized non-crossing trees avoiding patterns of lengt…
A simple bijection between binary trees and colored ternary trees
Yidong Sun
In this short note, we first present a simple bijection between binary trees and colored ternary trees and then derive a new identity related to generalized Catalan numbers.
The Star of David Rule
Yidong Sun
In this note, a new concept called {\em -matrix} is proposed, which is an infinite lower triangular matrix obeying the generalized rule of David star. Some basic properties of…
On the number of combinations without certain separations
Toufik Mansour, Yidong Sun
In this paper we enumerate the number of ways of selecting objects from objects arrayed in a line such that no two selected ones are separated by object…
Identities involving Narayana polynomials and Catalan numbers
Toufik Mansour, Yidong Sun
We first establish the result that the Narayana polynomials can be represented as the integrals of the Legendre polynomials. Then we represent the Catalan numbers in terms of the N…