A217807 Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).

1, 4, 29, 292, 3620, 51866, 827415, 14350467, 266218320

Offset

1,2

Links

Table of n, a(n) for n=1..9.

Andrew R. Conway, Anthony J. Guttmann, Paul Zinn-Justin, 1324-avoiding permutations revisited arXiv:1709.01248 [math.CO], 2017.

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: A302586 A302609 A181197 * A348651 A360584 A127770

Adjacent sequences: A217804 A217805 A217806 * A217808 A217809 A217810

Keyword

nonn,more

Author

N. J. A. Sloane, Oct 12 2012

Extensions

a(7)-a(9) from Lars Blomberg, Feb 17 2018

Status

approved