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 A177292 #6 Jan 18 2016 18:29:15 %S A177292 1,1,20,1680,51240,1173512,31006978,788946320,18721725280, %T A177292 435630242080,9998202729808,225310437716462 %N A177292 Number of permutations of 3 copies of 1..n with all adjacent differences <= 2 in absolute value. %C A177292 a(n) = (3n)!/6^n for n<=3. %Y A177292 Cf. A014606. %K A177292 nonn %O A177292 0,3 %A A177292 _R. H. Hardin_, May 06 2010 %E A177292 a(0) and a(11) from _Alois P. Heinz_, Jan 18 2016