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 A177294 #6 Jan 18 2016 18:32:37 %S A177294 1,1,20,1680,369600,168168000,41494252800,6923871998400, %T A177294 983114244363720,139528504017728552 %N A177294 Number of permutations of 3 copies of 1..n with all adjacent differences <= 4 in absolute value. %C A177294 a(n) = (3n)!/6^n for n<=5. %Y A177294 Cf. A014606. %K A177294 nonn %O A177294 0,3 %A A177294 _R. H. Hardin_, May 06 2010