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 A138487 #3 Aug 24 2012 10:50:01
%S A138487 3,13,1311,3113,2321,112213,133122,222123,134211,31121413,23411412,
%T A138487 22312413,23211432,32231421,21321423,23321421,21321423,23321421,
%U A138487 21321423,23321421,21321423,23321421,21321423,23321421,21321423
%N A138487 Say what you see in previous term, from the right, reporting total number for each digit encountered. Initial term is 3.
%C A138487 After a while sequence has period 2 -> {21321423,23321421}
%e A138487 To get the term after 112213, we say: one 3's, three 1's, two 2's, so 133122
%Y A138487 Cf. A063850, A022482, A005150, A005151, A006751, A006715, A006711, A022506-A022513, A138484-A138486, A138488-A138493.
%K A138487 easy,nonn,base
%O A138487 0,1
%A A138487 _Paolo P. Lava_ and _Giorgio Balzarotti_, Mar 20 2008