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 A270740 #41 Jan 16 2019 14:45:31
%S A270740 0,1,2,2,0,1,1,2,0,0,1,2,2,0,1,1,2,0,0,1,2,2,0,1,1,2,0,0,1,2,2,0,1,1,
%T A270740 2,0,0,1,2,2,0,1,1,2,0,0,1,2,2,0,1,1,2,0,0,1,2,2,0,1,1,2,0
%N A270740 Period 9: repeat 0,1,2,2,0,1,1,2,0.
%H A270740 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,-1,1,0,-1,1).
%F A270740 a(n) = (n - floor(n/3)) mod 3.
%F A270740 From _Chai Wah Wu_, Jun 04 2016: (Start)
%F A270740 a(n) = a(n-1) - a(n-3) + a(n-4) - a(n-6) + a(n-7) for n > 6.
%F A270740 G.f.: x*(1 + x - x^3 + 2*x^4)/((1 - x)*(1 + x^3 + x^6)). (End)
%t A270740 Table[Mod[n - Floor[n/3], 3], {n, 0, 120}] (* _Michael De Vlieger_, Mar 25 2016 *)
%t A270740 PadRight[{},120,{0,1,2,2,0,1,1,2,0}] (* _Harvey P. Dale_, Jan 16 2019 *)
%o A270740 (PARI) a(n) = (n - n\3) % 3; \\ _Michel Marcus_, Mar 22 2016
%Y A270740 Cf. A002264 (floor(n/3)), A010872 (n mod 3).
%K A270740 nonn,easy
%O A270740 0,3
%A A270740 _William Walkington_, Mar 22 2016