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 A177616 #5 Mar 02 2016 11:00:52 %S A177616 1,1,20,1680,369600,168168000,137150254800,182209829636934, %T A177616 368221858096998960 %N A177616 Number of permutations of 3 copies of 1..n avoiding adjacent step pattern up, down, down, down, down, down. %Y A177616 Cf. A014606. %K A177616 nonn %O A177616 0,3 %A A177616 _R. H. Hardin_, May 10 2010