A217803 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, 12, 108, 1202, 15234, 210696, 3102296, 47875884
Offset: 0
Links
- J. B. Lewis, Pattern Avoidance for Alternating Permutations and Reading Words of Tableaux, Ph. D. Dissertation, Department of Mathematics, MIT, 2012.
Extensions
a(6)-a(8) from Lars Blomberg, Jan 23 2018