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 A010677 #19 Aug 10 2023 14:06:23
%S A010677 0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,
%T A010677 0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,0,6,
%U A010677 0,6,0,6,0,6,0,6,0,6,0,6,0
%N A010677 Period 2: repeat (0,6).
%H A010677 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F A010677 a(n) = 3*[1-(-1)^n] = 6*(n mod 2). - _Paolo P. Lava_, Oct 20 2006
%F A010677 G.f. 6x/((1-x)(1+x)). - _R. J. Mathar_, Nov 21 2011
%t A010677 Table[6 Mod[n, 2], {n, 0, 50}] (* _Jinyuan Wang_, Feb 26 2020 *)
%t A010677 PadRight[{},100,{0,6}] (* _Harvey P. Dale_, Aug 10 2023 *)
%o A010677 (PARI) a(n)=n%2*6 \\ _Charles R Greathouse IV_, Jul 13 2016
%K A010677 nonn,easy
%O A010677 0,2
%A A010677 _N. J. A. Sloane_