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 A024764 #5 Mar 30 2012 18:35:23 %S A024764 2,3,23,31,233,311,2333 %N A024764 Every prefix prime in base 4 (written in base 4). %K A024764 nonn,base,fini,full %O A024764 1,1 %A A024764 _David W. Wilson_