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 A006140 #4 Dec 11 1999 03:00:00 %S A006140 1,1,-2,2,-2,1,0,1,-2,0,2,0,-1,-2,2,1,0,-2,2,-2 %N A006140 Erroneous version of A003406. %K A006140 dead %O A006140 0,3