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%I #24 Apr 01 2014 09:36:10
%S 1,2,6,24,115,590,3050,15576,78318,388208
%N Number of permutations w in S_n whose Kazhdan-Lusztig polynomial evaluated at q=1 is less than or equal to 2; P_{id,w}(1) <= 2.
%C This family of permutations is characterized by a finite set of patterns.
%D S. Billey and T. Braden, Lower bounds for Kazhdan-Lusztig polynomials from patterns, Transform. Groups 8 (2003), no. 4, 321-332.
%H FindStat - Combinatorial Statistic Finder, <a href="http://www.findstat.org/St000036">The evaluation of the Kazhdan-Lusztig polynomial P(id,w) for each permutation w in S_n evaluated at q = 1</a>
%H A. Woo, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v16i2r10">Permutations with Kazhdan-Lusztig polynomial P_{id,w}(q) = 1 + q^h with appendix by Sara Billey and Jonathan Weed</a>, The Electronic Journal of Combinatorics, Volume 16(2), 2009.
%Y Cf. A224316.
%K nonn,more
%O 1,2
%A _Sara Billey_, Apr 03 2013