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A217804 Number of alternating permutations on 2n+1 letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition). 0
1, 2, 16, 168, 2072, 28298, 414472, 6387436, 102316000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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: A337870 A181914 A089624 * A217799 A123555 A219446

Adjacent sequences:  A217801 A217802 A217803 * A217805 A217806 A217807

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Oct 12 2012

EXTENSIONS

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

STATUS

approved

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Last modified December 3 11:58 EST 2021. Contains 349462 sequences. (Running on oeis4.)