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 A138491 #3 Aug 24 2012 10:50:01
%S A138491 7,17,1711,3117,172113,13311217,17411223,1322311417,1741142322,
%T A138491 3213243117,1731331422,2214313317,1731331422,2214313317,1731331422,
%U A138491 2214313317,1731331422,2214313317,1731331422,2214313317,1731331422
%N A138491 Say what you see in previous term, from the right, reporting total number for each digit encountered. Initial term is 7.
%C A138491 After a while sequence has period 2 -> {1731331422,2214313317}
%e A138491 To get the term after 172113, we say: one 3's, three 1's, one 2's, one 7's, so 13311217
%Y A138491 Cf. A063850, A022482, A005150, A005151, A006751, A006715, A006711, A022506-A022513, A138484-A138490, A138492, A138493.
%K A138491 easy,nonn,base
%O A138491 0,1
%A A138491 _Paolo P. Lava_ and _Giorgio Balzarotti_, Mar 20 2008