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A217799
Number of alternating permutations on 2n+1 letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
32
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
J. B. Lewis, Pattern Avoidance for Alternating Permutations and Reading Words of Tableaux, Ph. D. Dissertation, Department of Mathematics, MIT, 2012.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Oct 12 2012
EXTENSIONS
a(6)-a(8) from Lars Blomberg, Jan 23 2018
STATUS
approved