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%I #32 May 19 2019 13:01:06
%S 12,66,572,5148,49764,497354,5118828,53745120,573308736,6191711526,
%T 67546215516,743008120140,8230246567620,91708459194066,
%U 1027134771622388,11555266154065920,130506535690613940
%N Number of aperiodic necklaces of n beads of 12 colors.
%H Vincenzo Librandi, <a href="/A032167/b032167.txt">Table of n, a(n) for n = 1..500</a>
%H C. G. Bower, <a href="/transforms2.html">Transforms (2)</a>
%H Y. Puri and T. Ward, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL4/WARD/short.html">Arithmetic and growth of periodic orbits</a>, J. Integer Seqs., Vol. 4 (2001), #01.2.1.
%H F. Ruskey, <a href="http://combos.org/necklace">Necklaces, Lyndon words, De Bruijn sequences, etc.</a>
%H F. Ruskey, <a href="/A000011/a000011.pdf">Necklaces, Lyndon words, De Bruijn sequences, etc.</a> [Cached copy, with permission, pdf format only]
%H <a href="/index/Lu#Lyndon">Index entries for sequences related to Lyndon words</a>
%F "CHK" (necklace, identity, unlabeled) transform of 12, 0, 0, 0...
%F a(n) = Sum_{d|n} mu(d)*12^(n/d)/n.
%F G.f.: Sum_{k>=1} mu(k)*log(1/(1 - 12*x^k))/k. - _Ilya Gutkovskiy_, May 19 2019
%t f[d_]:=MoebiusMu[d] 12^(n/d)/n; a[n_]:=Total[f/@Divisors[n]]; a[0]=1; Table[a[n], {n, 1, 30}] (* _Vincenzo Librandi_, Oct 14 2017 *)
%Y Column 12 of A074650.
%K nonn
%O 1,1
%A _Christian G. Bower_
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