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 A177309 #5 Mar 02 2016 11:20:10 %S A177309 1,1,3432,399072960,472518347558400,102038786510159790720, %T A177309 9792481437399343532438160 %N A177309 Number of permutations of 7 copies of 1..n with all adjacent differences <= 3 in absolute value. %C A177309 a(n) = (7n)!/5040^n for n<=4. %Y A177309 Cf. A172603. %K A177309 nonn %O A177309 0,3 %A A177309 _R. H. Hardin_, May 06 2010