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 A151589 #3 Mar 31 2012 12:35:18 %S A151589 0,5,105372,92123514,25367820672,3777055329267 %N A151589 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 8 adjacent element pairs in decreasing order. %K A151589 nonn %O A151589 4,2 %A A151589 _R. H. Hardin_ May 21 2009