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 A049091 #4 May 11 2007 03:00:00 %S A049091 2,3,7,11,23,31,43,47,59,67,71,79,83,103,107,131,139,167,179,191,211 %N A049091 Duplicate of A039787. %K A049091 dead %O A049091 1,1