

A224255


Number of permutations w in S_n whose KazhdanLusztig polynomial evaluated at q=1 is less than or equal to 2; P_{id,w}(1) <= 2.


1




OFFSET

1,2


COMMENTS

This family of permutations is characterized by a finite set of patterns.


REFERENCES

S. Billey and T. Braden, Lower bounds for KazhdanLusztig polynomials from patterns, Transform. Groups 8 (2003), no. 4, 321332.


LINKS

Table of n, a(n) for n=1..10.
FindStat  Combinatorial Statistic Finder, The evaluation of the KazhdanLusztig polynomial P(id,w) for each permutation w in S_n evaluated at q = 1
A. Woo, Permutations with KazhdanLusztig polynomial P_{id,w}(q) = 1 + q^h with appendix by Sara Billey and Jonathan Weed, The Electronic Journal of Combinatorics, Volume 16(2), 2009.


CROSSREFS

Cf. A224316.
Sequence in context: A177522 A216717 A174072 * A326348 A128088 A069657
Adjacent sequences: A224252 A224253 A224254 * A224256 A224257 A224258


KEYWORD

nonn,more


AUTHOR

Sara Billey, Apr 03 2013


STATUS

approved



