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 A177658 #5 Mar 02 2016 10:55:52 %S A177658 1,1,70,34650,63063000,304028985024,3200982922029530, %T A177658 64736431797158097635 %N A177658 Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, down, down, down, up. %Y A177658 Cf. A014608. %K A177658 nonn %O A177658 0,3 %A A177658 _R. H. Hardin_, May 10 2010