Restricted colored permutations and Chebyshev polynomials

Horse paths, restricted 132-avoiding permutations, continued fractions, and Chebyshev polynomials

Several authors have examined connections among 132-avoiding permutations, continued fractions, and Chebyshev polynomials of the second kind. In this paper we find analogues for some of these results for permutations π avoiding 132 and 1223 (there is no occurrence πi < πj < πj+1 such that 1 ≤ i ≤ j − 2) and provide a combinatorial interpretation for such permutations in terms of lattice paths. ...

Restricted Permutations and Chebyshev Polynomials

We study generating functions for the number of permutations in Sn 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.

2 00 2 Restricted Permutations and Chebyshev Polynomials

We study generating functions for the number of permutations in S n subject to two restrictions. One of the restrictions belongs to S 3 , while the other belongs to S k. It turns out that in a large variety of cases the answer can be expressed via Chebyshev polynomials of the second kind.

0 Restricted Permutations , Continued Fractions , and Chebyshev Polynomials

Restricted 132-alternating Permutations and Chebyshev Polynomials

A permutation is said to be alternating if it starts with rise and then descents and rises come in turn. In this paper we study the generating function for the number of alternating permutations on n letters that avoid or contain exactly once 132 and also avoid or contain exactly once an arbitrary pattern on k letters. In several interesting cases the generating function depends only on k and i...