Binary trees having a given number of nodes with 0, 1, and 2
Lotharingien de Combinatoire B38b, (1997), 6 pages, (Zbl 980.13720).
Comment on a paper by Helmut Prodinger in the same issue.
We give three combinatorial proofs for the number of binary trees having a
given number of nodes with 0, 1, and 2 children. We extend these results
to ordered trees with given distribution of nodes according to their numbers
Last update: July 11, 2007.