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 A177311 #7 Mar 02 2016 11:24:23 %S A177311 1,1,12870,9465511770,580132098966420,19840440079542390102, %T A177311 1061489454895820193068774 %N A177311 Number of permutations of 8 copies of 1..n with all adjacent differences <= 2 in absolute value. %C A177311 a(n) = (8n)!/40320^n for n<=3. %Y A177311 Cf. A172609. %K A177311 nonn %O A177311 0,3 %A A177311 _R. H. Hardin_, May 06 2010