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 A014021 #33 Dec 14 2023 05:44:55
%S A014021 1,0,1,0,0,0,-1,0,-1,0,0,0,1,0,1,0,0,0,-1,0,-1,0,0,0,1,0,1,0,0,0,-1,0,
%T A014021 -1,0,0,0,1,0,1,0,0,0,-1,0,-1,0,0,0,1,0,1,0,0,0,-1,0,-1,0,0,0,1,0,1,0,
%U A014021 0,0,-1,0,-1,0,0,0,1,0,1,0,0,0,-1,0,-1
%N A014021 Inverse of 12th cyclotomic polynomial.
%C A014021 Periodic with period length 12. - _Ray Chandler_, Apr 03 2017
%H A014021 Vincenzo Librandi, <a href="/A014021/b014021.txt">Table of n, a(n) for n = 0..1000</a>
%H A014021 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0, 1, 0, -1).
%H A014021 <a href="/index/Pol#poly_cyclo_inv">Index to sequences related to inverse of cyclotomic polynomials</a>
%F A014021 G.f.: 1 / ( 1-x^2+x^4 ). - _R. J. Mathar_, Mar 11 2011
%p A014021 with(numtheory,cyclotomic); c := n->series(1/cyclotomic(n,x),x,80);
%t A014021 CoefficientList[Series[1/Cyclotomic[12, x], {x, 0, 100}], x] (* _Vincenzo Librandi_, Apr 03 2014 *)
%t A014021 LinearRecurrence[{0,1,0,-1},{1,0,1,0},100] (* or *) PadRight[{},100,{1,0,1,0,0,0,-1,0,-1,0,0,0}] (* _Harvey P. Dale_, Oct 12 2017 *)
%o A014021 (PARI) Vec(1/polcyclo(12)+O(x^99)) \\ _Charles R Greathouse IV_, Mar 24 2014
%o A014021 (Magma) &cat[[1,0,1,0,0,0,-1,0,-1,0,0,0]: n in [0..15]]; // _Vincenzo Librandi_, Apr 03 2014
%K A014021 sign,easy
%O A014021 0,1
%A A014021 _Simon Plouffe_