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 A049335 #1 Dec 11 1999 03:00:00 %S A049335 1,240,2160,6720,17280 %N A049335 Erroneous version of A004009. %K A049335 dead %O A049335 0,2