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%I #20 Jun 04 2022 04:29:42
%S 4,5,5,7,5,10,5,9,7,10,5,14,5,10,10,11,5,14,5,14,10,10,5,18,7,10,9,14,
%T 5,20,5,13,10,10,10,20,5,10,10,18,5,20,5,14,14,10,5,22,7,14,10,14,5,
%U 18,10,18,10,10,5,28,5,10,14,15,10,20,5,14,10,20,5,26,5,10,14,14,10,20,5
%N a(n) = 2 * Sum_{d|n} 2^mu(d).
%H Antti Karttunen, <a href="/A071570/b071570.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F Asymptotically: Sum_{k=1..n} a(k) = 2*C*n*log(n) + O(n*log(n)) with C = 1.1...
%t a[n_] := 2 * DivisorSum[n, 2^MoebiusMu[#] &]; Array[a, 100] (* _Amiram Eldar_, Jun 04 2022 *)
%o (PARI) for(n=1,100,print1(2*sumdiv(n,d,2^moebius(d)),","))
%Y Cf. A008683.
%K nonn,easy
%O 1,1
%A _Benoit Cloitre_, May 31 2002
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