Séminaire Lotharingien de Combinatoire, B47c (2002), 17 pp.
Toufik Mansour and Alek Vainshtein
Restricted Permutations and Chebyshev Polynomials
We study generating functions for the number of permutations in
subject to two restrictions. One of the restrictions belongs to S3,
while the other belongs to Sk. It turns out that in a large
variety of cases
the answer can be expressed via Chebyshev polynomials of the second kind.
Received: June 26, 2001; Revised: December 12, 2001; Accepted: January 3, 2002.
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