Schröder Triangles, Paths, and Parallelogram Polyominoes
Dipart. di Sistemi e Informatica
Universitá di Firenze, Firenze, Italy
Email address: firstname.lastname@example.org
Robert A. Sulanke
This paper considers combinatorial interpretations for two
triangular recurrence arrays containing
the Schröder numbers
sn = 1, 1, 3, 11, 45, 197, ...
rn = 1, 2, 6, 22, 90, 394, ... , for
n = 0, 1, 2, ....
These interpretations involve the
enumeration of constrained lattice paths and bicolored
In addition to two recent inductive constructions of zebras and their associated
generating trees, we present two new ones and a bijection between zebras and
constrained lattice paths.
We use the constructions with generating
function methods to count sets of zebras
with respect to natural parameters.
Boise State University, Boise, ID, U.S.A
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Received Apr. 21 1998 and in revised form May 23 1998. Published in Journal of Integer Sequences May 29, 1998.
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