This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A217823 #12 Aug 06 2023 16:40:56
%S A217823 1,1,9,153,3579,101630,3288871
%N A217823 Number of permutations of length 3n with descent set {3, 6, ...} that avoid a certain pattern of length 4 or 5 (see Lewis, 2012, Appendix, for precise definition).
%C A217823 Is this the same sequence as A361190?
%H A217823 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 A217823 Cf. A181197, A217799-A217830, A361190.
%K A217823 nonn,more
%O A217823 0,3
%A A217823 _N. J. A. Sloane_, Oct 13 2012
%E A217823 a(5)-a(6) from _Lars Blomberg_, Mar 09 2018
%E A217823 a(0)=1 prepended by _Alois P. Heinz_, Jul 31 2023