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 A123458 #18 Nov 30 2015 21:03:15 %S A123458 1,2,4,9,21,56,164,557,2223,10766 %N A123458 Duplicate of A048194. %K A123458 dead %O A123458 1,2