Counting occurrences of 231 in an involution

被引：3
|
作者：
Mansour, T [1 ]
Yan, SHF
Yang, LLM
机构：
[1] Univ Haifa, Dept Math, IL-31905 Haifa, Israel
[2] Nankai Univ, Ctr Combinator, LPMC, Tianjin 300071, Peoples R China
来源：
DISCRETE MATHEMATICS | 2006年 / 306卷 / 06期
关键词：
restricted permutations; restricted involutions; generating functions;
D O I：
10.1016/j.disc.2006.01.011
中图分类号：
O1 [数学];
学科分类号：
0701 ; 070101 ;
摘要：
We study the generating function for the number of involutions on n letters containing exactly r >= 0 occurrences of 231. It is shown that finding this function for a given r amounts to a routine check of all involutions of length at most 2r + 2. (c) 2006 Elsevier B.V. All rights reserved.
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页码：564 / 572
页数：9
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