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 A134977 #22 Dec 12 2023 08:52:58
%S A134977 1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,
%T A134977 0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,
%U A134977 2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2,1,4,2,3,0,2
%N A134977 Period 6: repeat [1, 4, 2, 3, 0, 2].
%C A134977 Northwest diagonal sums of A134658, omitting row 0.
%H A134977 Vincenzo Librandi, <a href="/A134977/b134977.txt">Table of n, a(n) for n = 0..1000</a>
%H A134977 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,-1,1).
%F A134977 O.g.f.: -1/(x+1)-2/(x-1)+x/(x^2-x+1). a(n) = 2-(-1)^n+A010892(n-1). - _R. J. Mathar_, Feb 08 2008
%F A134977 From _Wesley Ivan Hurt_, Jun 18 2016: (Start)
%F A134977 a(n) = a(n-1) - a(n-3) + a(n-4) for n>3.
%F A134977 a(n) = (6-3*cos(n*Pi)+2*sqrt(3)*sin(n*Pi/3))/3. (End)
%p A134977 A134977:=n->[1, 4, 2, 3, 0, 2][(n mod 6)+1]: seq(A134977(n), n=0..100); # _Wesley Ivan Hurt_, Jun 18 2016
%t A134977 Flatten[Table[{1, 4, 2, 3, 0, 2}, {20}]] (* _Wesley Ivan Hurt_, Jun 18 2016 *)
%t A134977 PadRight[{}, 100, {1, 4, 2, 3, 0, 2}] (* _Vincenzo Librandi_, Jun 19 2016 *)
%o A134977 (Magma) &cat[[1, 4, 2, 3, 0, 2]^^20]; // _Wesley Ivan Hurt_, Jun 18 2016
%Y A134977 Cf. A010892, A119910, A130784, A131756, A134658.
%K A134977 nonn,easy
%O A134977 0,2
%A A134977 _Paul Curtz_, Feb 04 2008