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 A279554 #18 Dec 31 2018 06:16:57 %S A279554 1,1,2,5,15,51,188,733,2979,12495,53708,235396,1048168,4728757, %T A279554 21569339,99309057,460932778,2154402107 %N A279554 Number of length n inversion sequences avoiding the patterns 010, 101, 120, 201, and 210. %C A279554 A length n inversion sequence e_1e_2...e_n is a sequence of integers where 0 <= e_i <= i-1. The term a(n) counts those length n inversion sequences with no entries e_i, e_j, e_k (where i<j<k) such that e_i <> e_j <> e_k and e_i >= e_k. This is the same as the set of length n inversion sequences avoiding 010, 101, 120, 201, and 210. %H A279554 Megan A. Martinez, Carla D. Savage, <a href="https://arxiv.org/abs/1609.08106">Patterns in Inversion Sequences II: Inversion Sequences Avoiding Triples of Relations</a>, arXiv:1609.08106 [math.CO], 2016-2018. %e A279554 The length 3 inversion sequences are 000, 001, 002, 011, 012. %e A279554 The length 4 inversion sequences are 0000, 0001, 0002, 0003, 0011, 0012, 0013, 0021, 0022, 0023, 0111, 0112, 0113, 0122, 0123. %Y A279554 Cf. A263777, A263778, A263779, A263780, A279551, A279552, A279553, A279555, A279556, A279557, A279558, A279559, A279560, A279561, A279562, A279563, A279564, A279565, A279566, A279567, A279568, A279569, A279570, A279571, A279572, A279573. %K A279554 nonn,more %O A279554 0,3 %A A279554 _Megan A. Martinez_, Dec 15 2016 %E A279554 a(10)-a(11) from _Alois P. Heinz_, Feb 24 2017 %E A279554 a(12)-a(17) from _Bert Dobbelaere_, Dec 30 2018