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 A131718 #46 Sep 09 2024 14:55:58
%S A131718 1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,
%T A131718 2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,
%U A131718 2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,2
%N A131718 Period 6: repeat [1, 1, 2, 1, 2, 1].
%C A131718 Decimal expansion of 112121/999999. - _Klaus Brockhaus_, May 21 2010
%H A131718 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,1).
%F A131718 G.f.: (1+x+2*x^2+x^3+2*x^4+x^5)/((1-x)*(1+x)*(x^2+x+1)*(x^2-x+1)). - _R. J. Mathar_, Jan 17 2008
%F A131718 From _Wesley Ivan Hurt_, Jun 17 2016: (Start)
%F A131718 a(n) = a(n-6) for n>5.
%F A131718 a(n) = (4 + cos(n*Pi) - cos(n*Pi/3) - cos(2*n*Pi/3))/3. (End)
%p A131718 A131718:=n->(4+cos(n*Pi)-cos(n*Pi/3)-cos(2*n*Pi/3))/3: seq(A131718(n), n=0..100); # _Wesley Ivan Hurt_, Jun 17 2016
%t A131718 Flatten[Table[{1, 1, 2, 1, 2, 1}, {20}]] (* _Wesley Ivan Hurt_, Jun 17 2016 *)
%o A131718 (Magma) &cat[[1, 1, 2, 1, 2, 1]: k in [1..30]]; // _Vincenzo Librandi_, Nov 23 2010
%o A131718 (PARI) a(n)=[1,1,2,1,2,1][n%6+1] \\ _Charles R Greathouse IV_, Jun 02 2011
%Y A131718 Cf. A178149 (decimal expansion of (15+sqrt(1365))/30). - _Klaus Brockhaus_, May 21 2010
%K A131718 nonn,easy,less
%O A131718 0,3
%A A131718 _Paul Curtz_, Sep 15 2007
%E A131718 More terms from _Klaus Brockhaus_, May 21 2010