A217799 Number of alternating permutations on 2n+1 letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).

1, 2, 16, 168, 2112, 30030, 466752, 7759752, 135980416

Offset

0,2

Comments

Probably the same as A123555 for n>0. - R. J. Mathar, Nov 22 2023

Links

Table of n, a(n) for n=0..8.

J. B. Lewis, Pattern Avoidance for Alternating Permutations and Reading Words of Tableaux, Ph. D. Dissertation, Department of Mathematics, MIT, 2012.

Crossrefs

Cf. A181197, A217799-A217830.

Sequence in context: A181914 A089624 A217804 * A123555 A219446 A215702

Adjacent sequences: A217796 A217797 A217798 * A217800 A217801 A217802

Keyword

nonn,more

Author

N. J. A. Sloane, Oct 12 2012

Extensions

a(6)-a(8) from Lars Blomberg, Jan 23 2018

Status

approved