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A217803
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, 12, 108, 1202, 15234, 210696, 3102296, 47875884
OFFSET
0,2
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