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 A243245 #19 Dec 01 2015 08:42:47 %S A243245 0,0,1,3,15,93,794,10850,259700,11706739 %N A243245 Duplicate of A128240. %K A243245 dead %O A243245 1,4