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 A105607 #17 Jun 06 2025 08:05:17
%S A105607 1,2,6,8,44,10,328,56,408,76,18272,52,136384,568,3856,3104,7598336,
%T A105607 424,56714752,2896,215104,31648,3159738368,3088,536013824,236224,
%U A105607 71910912,161344,1313964867584,2320,9807567290368,9634304,667730944,13160704,37860806656,172864,4078438577864704,98232832,37201186816,9584896
%N A105607 Sylvester cyclotomic numbers for A002605.
%C A105607 Primitive parts of A002605.
%H A105607 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SylvesterCyclotomicNumber.html">Sylvester Cyclotomic Number</a>.
%F A105607 a(n) = A002605(n)/A105606(n); a(n) = Product_{k=1..n-1, gcd(n, k)=1} (1+sqrt(3))-(1-sqrt(3))*exp(2*Pi*i*k/n), i = sqrt(-1). - _Robert G. Wilson v_, Aug 02 2005
%t A105607 f[n_] := FullSimplify[ Expand[ Times @@ ((1+Sqrt[3])-(1-Sqrt[3])*Exp[2Pi*I*Select[Range[n-1], GCD[ #, n] == 1 &]/n])]]; Table[ f[n], {n, 1, 32}] (* _Robert G. Wilson v_, Aug 02 2005 *)
%Y A105607 Cf. A002605, A105608, A105609.
%K A105607 nonn
%O A105607 1,2
%A A105607 _Paul Barry_, Apr 15 2005
%E A105607 More terms from _David Wasserman_, May 06 2008