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 A177297 #6 Jan 18 2016 18:33:11 %S A177297 1,1,20,1680,369600,168168000,137225088000,182509367040000, %T A177297 369398958888960000,510778379991559680000 %N A177297 Number of permutations of 3 copies of 1..n with all adjacent differences <= 7 in absolute value. %C A177297 a(n) = (3n)!/6^n for n<=8. %Y A177297 Cf. A014606. %K A177297 nonn %O A177297 0,3 %A A177297 _R. H. Hardin_, May 06 2010