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 A069538 #4 May 11 2007 03:00:00 %S A069538 3,12,21,30,102,111,120,201,210,300,1002,1011,1020,1101,1110,1200,2001 %N A069538 Duplicate of A052217. %K A069538 dead %O A069538 0,1