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A256196 Number of permutations in S_n that avoid the pattern 31524. 1
1, 1, 2, 6, 24, 119, 694, 4579, 33216, 259401, 2147525, 18632512, 167969934, 1563027614, 14937175825, 146016423713, 1455402205257, 14753501614541, 151783381341695, 1582029822426003, 16681492660789425, 177726496203056670, 1911230701872865231, 20726637978574528119 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Nathan Clisby, Andrew R. Conway, Anthony J. Guttmann, Yuma Inoue, Classical length-5 pattern-avoiding permutations, arXiv:2109.13485 [math.CO], 2021.
Zvezdelina Stankova-Frenkel and Julian West, A new class of Wilf-equivalent permutations, arXiv:math/0103152 [math.CO], 2001.
MATHEMATICA
avoid[n_, pat_] := Module[{p1 = pat[[1]], p2 = pat[[2]], p3 = pat[[3]], p4 = pat[[4]], p5 = pat[[5]], lseq = {}, i, p,
lpat = Subsets[(n + 1) - Range[n], {Length[pat]}],
psn = Permutations[Range[n]]},
For[i = 1, i <= Length[lpat], i++,
p = lpat[[i]];
AppendTo[lseq, Select[psn, MemberQ[#, {___, p[[p1]], ___, p[[p2]], ___, p[[p3]], ___, p[[p4]], ___, p[[p5]], ___}, {0}] &]];
]; n! - Length[Union[Flatten[lseq, 1]]]];
Table[avoid[n, {3, 1, 5, 2, 4}], {n, 0, 8}] (* Robert Price, Mar 27 2020 *)
CROSSREFS
Representatives for the 16 Wilf-equivalence patterns of length 5 are given in A116485, A047889, and A256195-A256208.
Cf. A099952.
Sequence in context: A264781 A224316 A256195 * A256197 A256198 A256199
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 19 2015
EXTENSIONS
a(14)-a(16) from Bert Dobbelaere, Mar 18 2021
More terms from Anthony Guttmann, Sep 29 2021
STATUS
approved

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Last modified March 1 06:29 EST 2024. Contains 370430 sequences. (Running on oeis4.)