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 A087578 #3 May 11 2007 03:00:00 %S A087578 3,7,13,31,127,307,1093,1723,2801,3541,5113,8011,8191,10303,17293, %T A087578 19531 %N A087578 Duplicate of A023195. %K A087578 dead %O A087578 1,1