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%I #13 Dec 23 2017 04:49:25
%S 1,2,3,4,5,3,7,8,9,5,11,2,13,7,15,16,17,18,19,5,7,11,23,12,25,13,27,
%T 14,29,15,31,32,33,17,35,12,37,19,13,2,41,7,43,22,45,23,47,24,49,50,
%U 51,13,53,27,11,28,19,29,59,5,61,31,3,64,65,33,67,17,69,35
%N a(n) = denominator(A206369(n))/n.
%H Michel Marcus, <a href="/A294650/b294650.txt">Table of n, a(n) for n = 1..10000</a>
%H László Tóth, <a href="http://arxiv.org/abs/1111.4842">A survey of the alternating sum-of-divisors function</a>, arXiv:1111.4842 [math.NT], 2011-2014.
%t (* b = A209369 *) b[n_] := n*DivisorSum[n, LiouvilleLambda[#]/# &];
%t a[n_] := Denominator[b[n]/n];
%t Array[a, 100] (* _Jean-François Alcover_, Dec 04 2017 *)
%o (PARI) rhope(p, e) = my(s=1); for(i=1, e, s=s*p + (-1)^i); s;
%o rho(n) = my(f=factor(n)); prod(i=1, #f~, rhope(f[i, 1], f[i, 2]));
%o a(n) = denominator(rho(n)/n);
%Y Cf. A127724 (k-imperfect), A206369, A294649 (numerator).
%Y A225680 is a subsequence (on squarefree indices). - _Michel Marcus_, Dec 22 2017
%K nonn,frac
%O 1,2
%A _Michel Marcus_, Nov 06 2017
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