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 A138488 #3 Aug 24 2012 10:50:01
%S A138488 4,14,1411,3114,142113,13311214,14411223,13223124,14322123,23322114,
%T A138488 14213223,23322114
%N A138488 Say what you see in previous term, from the right, reporting total number for each digit encountered. Initial term is 4.
%C A138488 After a while sequence has period 2 -> {23322114,14213223}
%e A138488 To get the term after 142113, we say: one 3's, three 1's, one 2's, one 4's, so 13311214
%Y A138488 Cf. A063850, A022482, A005150, A005151, A006751, A006715, A006711, A022506-A022513, A138484-A138487, A138489-A138493.
%K A138488 easy,nonn,base
%O A138488 0,1
%A A138488 _Paolo P. Lava_ and _Giorgio Balzarotti_, Mar 20 2008