Counting occurences of 132 in a permutation
Toufik Mansour, Alek Vainshtein · arXiv (Cornell University) · 2001
We study the generating function for the number of permutations on n letters containing exactly $r\gs0$ occurences of 132. It is shown that finding this function for a given r amounts to a routine check of all permutations in $S_{2r}$.