Journal of Integer Sequences, Vol. 18 (2015), Article 15.5.8

The Boundary of Ordered Trees

Dennis E. Davenport and Louis W. Shapiro
Mathematics Department
Howard University
Washington, DC 20059

Lara K. Pudwell
Department of Mathematics and Statistics
Valparaiso University
Valparaiso, IN 46383

Leon C. Woodson
Department of Mathematics
Morgan State University
Baltimore, MD 21251


In this paper we compute the distribution of several statistics on the set of rooted ordered trees. In particular, we determine the number of boundary edges, the number of singleton boundary edges, and the analogous values when edges may take on one of k colors.

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(Concerned with sequences A000108 A000245 A000344 A000957 A000984 A001700 A014137 A068551 A228180 A228197 A228343.)

Received October 2 2013; revised versions received September 11 2014; May 27 2015. Published in Journal of Integer Sequences, May 28 2015.

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