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 A089769 #3 Jun 29 2008 03:00:00 %S A089769 2,3,5,7,11,19,41,61,89,101,109,149,181,401,409,449,491,499,601,691, %T A089769 809 %N A089769 Duplicate of A033274. %K A089769 dead %O A089769 1,1