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 A021307 #20 Apr 18 2024 18:20:53
%S A021307 0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,
%T A021307 3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,
%U A021307 0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3,3,0,0,3
%N A021307 Decimal expansion of 1/303.
%H A021307 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,-1,1).
%F A021307 From _Chai Wah Wu_, Apr 18 2024: (Start)
%F A021307 a(n) = a(n-1) - a(n-2) + a(n-3) for n > 2.
%F A021307 G.f.: -3*x^2/((x - 1)*(x^2 + 1)). (End)
%F A021307 Equals 3*A021913. - _Hugo Pfoertner_, Apr 18 2024
%e A021307 0.003300330033003300330033...
%t A021307 Join[{0,0},RealDigits[1/303,10,120][[1]]] (* or *) PadRight[{},120,{0,0,3,3}] (* _Harvey P. Dale_, May 29 2017 *)
%Y A021307 Cf. A021913.
%K A021307 nonn,cons,easy
%O A021307 0,3
%A A021307 _N. J. A. Sloane_