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 A151586 #3 Mar 31 2012 12:35:18 %S A151586 0,184,41450,2698344,101727276,2846840080,66502921806,1382518990400 %N A151586 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 5 adjacent element pairs in decreasing order. %K A151586 nonn %O A151586 3,2 %A A151586 _R. H. Hardin_ May 21 2009