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 A187181 #18 Nov 05 2015 10:53:09
%S A187181 1,1,1,2,2,2,3,4,3,4,3,4,5,5,5,6,7,6,7,6,7,8,8,8,9,10,9,10,9,10,11,11,
%T A187181 11,12,13,12,13,12,13,14,14,14,15,16,15,16,15,16,17,17,17,18,19,18,19,
%U A187181 18,19,20,20,20,21,22,21,22,21,22,23,23,23,24,25,24,25,24,25,26,26,26,27,28,27,28,27,28,29,29,29,30,31,30,31,30,31,32,32,32,33,34,33,34
%N A187181 Parse the infinite string 012012012012... into distinct phrases 0, 1, 2, 01, 20, 12, 012, ...; a(n) = length of n-th phrase.
%C A187181 See A187180 for details.
%H A187181 Ray Chandler, <a href="/A187181/b187181.txt">Table of n, a(n) for n = 1..1000</a>
%H A187181 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 0, 0, 0, 0, 0, 0, 1, -1).
%F A187181 After the initial block of three 1's, the sequence is quasi-periodic with period 9, increasing by 3 after each block.
%F A187181 From _Colin Barker_, Nov 05 2015: (Start)
%F A187181 a(n) = a(n-1) + a(n-9) - a(n-10) for n>12.
%F A187181 G.f.: x*(x^11-x^10-x^8+x^7+x^6+x^3+1) / ((x-1)^2*(x^2+x+1)*(x^6+x^3+1)).
%F A187181 (End)
%e A187181 The sequence begins
%e A187181 1 1 1
%e A187181 2 2 2 3 4 3 4 3 4
%e A187181 5 5 5 6 7 6 7 6 7
%e A187181 8 8 8 9 10 9 10 9 10
%e A187181 11 11 11 12 13 12 13 12 13
%e A187181 14 14 14 15 16 15 16 15 16 ...
%t A187181 Join[{1, 1},LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 1, -1},{1, 2, 2, 2, 3, 4, 3, 4, 3, 4},98]] (* _Ray Chandler_, Aug 26 2015 *)
%o A187181 (PARI) Vec(x*(x^11-x^10-x^8+x^7+x^6+x^3+1)/((x-1)^2*(x^2+x+1)*(x^6+x^3+1)) + O(x^100)) \\ _Colin Barker_, Nov 05 2015
%Y A187181 See A187180-A187188 for alphabets of size 2 through 10.
%K A187181 nonn,easy
%O A187181 1,4
%A A187181 _N. J. A. Sloane_, Mar 06 2011