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 A005780 #3 Dec 11 1999 03:00:00 %S A005780 1,0,1,3,38,680 %N A005780 Erroneous version of A033678. %K A005780 dead %O A005780 1,4