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 A177612 #5 Jan 25 2016 16:28:02 %S A177612 1,1,20,1680,362082,159459279,124951069219,158754672447498, %T A177612 305860462403616044 %N A177612 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, up, up, up. %Y A177612 Cf. A014606. %K A177612 nonn %O A177612 0,3 %A A177612 _R. H. Hardin_, May 10 2010