Layered Restrictions and Chebyshev
نویسندگان
چکیده
Abstract. A permutation is called layered if it consists of the disjoint union of substrings (layers) so that the entries decrease within each layer, and increase between the layers. We find the generating function for the number of permutations on n letters avoiding (1, 2, 3) and a layered permutation on k letters. In the most interesting case of two layers, the generating function depends only on k and is expressed via Chebyshev polynomials of the second kind.
منابع مشابه
Layered Restrictions And
Abstract. A permutation is called layered if it consists of the disjoint union of substrings (layers) so that the entries decrease within each layer, and increase between the layers. We find the generating function for the number of permutations on n letters avoiding (1, 2, 3) and a layered permutation on k letters. In the most interesting case of two layers, the generating function depends onl...
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