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%I #15 Nov 22 2023 04:21:36
%S 1,2,16,168,2112,30030,466752,7759752,135980416
%N Number of alternating permutations on 2n+1 letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).
%C Probably the same as A123555 for n>0. - _R. J. Mathar_, Nov 22 2023
%H J. B. Lewis, <a href="https://dspace.mit.edu/handle/1721.1/73444">Pattern Avoidance for Alternating Permutations and Reading Words of Tableaux</a>, Ph. D. Dissertation, Department of Mathematics, MIT, 2012.
%Y Cf. A181197, A217799-A217830.
%K nonn,more
%O 0,2
%A _N. J. A. Sloane_, Oct 12 2012
%E a(6)-a(8) from _Lars Blomberg_, Jan 23 2018
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