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 A124252 #7 Mar 19 2014 19:48:04 %S A124252 0,10,100,110,200,210,1000,1010,1100,1110,1200,1210,2000,2010,2100, %T A124252 2110,2200,2210,3000,3010,3100,3110,3200,3210,10000,10010,10100,10110, %U A124252 10200,10210,11000,11010,11100,11110,11200,11210,12000,12010,12100,12110,12200 %N A124252 10 times A007623. %H A124252 Wikipedia, <a href="http://en.wikipedia.org/wiki/Factoradic">Factorial base</a> %K A124252 nonn %O A124252 0,2 %A A124252 _N. J. A. Sloane_, following a suggestion from Jonathan Vos Post, Dec 15 2006