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 A048239 #5 May 19 2006 03:00:00 %S A048239 1,1,2,4,6,11,19,33,55,95,158,267,442,731,1193,1947,3137,5039,8026 %N A048239 Duplicate of A000786. %K A048239 dead %O A048239 1,3