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 A063671 #18 Nov 02 2016 03:34:03
%S A063671 10,11,11,111,101,11111,111,1111111,10001,1001001,11111,11111111111,
%T A063671 10101,1111111111111,1111111,110111011,100000001,11111111111111111,
%U A063671 1001001,1111111111111111111,101010101,1101101011011,11111111111
%N A063671 Positions of nonzero coefficients in cyclotomic polynomial Phi_n(x), A063670 in binary.
%C A063671 a(0) could also be 1. - _T. D. Noe_, Oct 29 2007
%H A063671 T. D. Noe, <a href="/A063671/b063671.txt">Table of n, a(n) for n=0..300</a>
%H A063671 <a href="/index/Cy#CyclotomicPolynomialsCoefficients">Index entries for cyclotomic polynomials, positions of coefficients</a>
%F A063671 a(n) = A063697(n) (the positive terms) + A063699(n) (the negative terms) (computed in any base, up to n=104).
%e A063671 Phi_15(x) = x^8 - x^7 + x^5 - x^4 + x^3 - x + 1, thus the 1-bits of a(15) are at positions 0,1,3,4,5,7 and 8, thus we get a(15) = 110111011.
%p A063671 map(convert, A063670,binary);
%t A063671 a[n_] := FromDigits[Abs[CoefficientList[Cyclotomic[n, x], x]]]; a[0]=10;Table[a[n], {n, 0, 22}] (* _Jean-François Alcover_, Nov 02 2016 *)
%Y A063671 Cf. A063672, A063697, A063699.
%Y A063671 Cf. A013595.
%K A063671 nonn,base,nice
%O A063671 0,1
%A A063671 _Antti Karttunen_, Aug 03 2001