OFFSET

1,2

COMMENTS

These permutations are sometimes called "superpatterns".

A upper bound is ceiling((n^2+1)/2), see Engen and Vatter. A simple lower bound is n^2/e^2, which has been improved to 1.000076 n^2/e^2 by Chroman, Kwan, and Singhal.

LINKS

Richard Arratia, On the Stanley-Wilf conjecture for the number of permutations avoiding a given pattern, Electron. J. Combin., 6 (1999), Note 1, 4 pp.

Zachary Chroman, Matthew Kwan, and Mihir Singhal, Lower bounds for superpatterns and universal sequences, arXiv:2004.02375 [math.CO], 2020-2021.

Michael Engen and Vincent Vatter, Containing all permutations, Amer. Math. Monthly, 128 (2021), 4-24, section 6; arXiv preprint, arXiv:1810.08252 [math.CO], 2018-2020.

Henrik Eriksson, Kimmo Eriksson, Svante Linusson, and Johan Wästlund, Dense packing of patterns in a permutation, Ann. Comb., 11 (2007), 459-470.

Alison Miller, Asymptotic bounds for permutations containing many different patterns, J. Combin. Theory Ser. A, 116 (2009), 92-108.

EXAMPLE

For n=3, the permutation 25314 contains all 6 permutations of length 3, but no shorter permutation does, so a(3)=5.

CROSSREFS

KEYWORD

nonn,more

AUTHOR

Vincent Vatter, Mar 13 2021

STATUS

approved