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 A123594 #14 Mar 07 2015 00:43:52
%S A123594 1,1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,0,0,1,1,0,1,0,0,1,0,1,1,0,0,1,0,0,
%T A123594 1,0,1,1,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,0,1,1,0,1,1,0,0,1,0,1,1,0,1,1,
%U A123594 0,0,1,0,0,1,0,1,1,0,1,0,0,1,1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,0,0,1,1,0,1,0
%N A123594 Unique sequence of 0's and 1's which are either repeated or not repeated with the following property: when the sequence is 'coded' in writing down a 1 when an element is repeated and a 0 when it is not repeated and by putting the initial element in front of the sequence thus obtained, the above sequence appears.
%H A123594 Vantieghem Emmanuel, Nov 14 2006, <a href="/A123594/b123594.txt">Table of n, a(n) for n = 1..620</a>
%F A123594 a(n+2) = A000002(n)-1. - _Danny Rorabaugh_, Mar 04 2015
%t A123594 a = {1, 1, 0}; i = 2; Label[be]; i += 1; t = Part[a, i]; If[t == 0, b = {a, 1 - Part[a, Length[a]]}; a := Flatten[b], b = {a, Part[a, Length[a]]}; a := Flatten[b]; b = {a, 1 - Part[a, Length[a]]}; a := Flatten[b]]; If[i > 1000, Print[a], Goto[be]]
%Y A123594 Cf. A000002.
%K A123594 easy,nonn
%O A123594 1,1
%A A123594 _Emmanuel Vantieghem_, Nov 14 2006