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 A021499 #32 Jul 08 2025 08:32:04
%S A021499 0,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,
%T A021499 2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,
%U A021499 2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0,2,0
%N A021499 Decimal expansion of 1/495.
%C A021499 0, then repeat 0, 2. [_Arkadiusz Wesolowski_, Jul 22 2011]
%H A021499 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F A021499 a(n) = 1 + (-1)^n - 2*0^n = (-1 - A033999(n))*A062157(n). [_Arkadiusz Wesolowski_, Jul 22 2011]
%F A021499 G.f.: 2*x^2/(1-x^2). - _Bruno Berselli_, Jul 22 2011
%t A021499 Join[{0,0},RealDigits[1/495,10,120][[1]]] (* or *) PadRight[{0},120,{2,0}] (* _Harvey P. Dale_, Dec 13 2020 *)
%Y A021499 A010673 shifted right.
%K A021499 nonn,cons
%O A021499 0,3
%A A021499 _N. J. A. Sloane_