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 A123464 #10 Dec 03 2015 10:32:23 %S A123464 1,2,4,8,16,32,64,128,256,512 %N A123464 Duplicate of A011782. %K A123464 dead %O A123464 1,2