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 A217830 #8 Oct 08 2018 09:30:38
%S A217830 1,19,1513,211425,40607753,9694117094
%N A217830 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).
%H A217830 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 A217830 Cf. A181197, A217799-A217830.
%K A217830 nonn,more
%O A217830 1,2
%A A217830 _N. J. A. Sloane_, Oct 13 2012
%E A217830 a(5)-a(6) from _Lars Blomberg_, Mar 09 2018