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Sum of squarefree divisors of n that have an even number of prime factors.
6

%I #8 Sep 05 2018 06:12:34

%S 1,1,1,1,1,7,1,1,1,11,1,7,1,15,16,1,1,7,1,11,22,23,1,7,1,27,1,15,1,32,

%T 1,1,34,35,36,7,1,39,40,11,1,42,1,23,16,47,1,7,1,11,52,27,1,7,56,15,

%U 58,59,1,32,1,63,22,1,66,62,1,35,70,60,1,7,1,75,16,39,78,72,1,11,1,83,1,42,86,87,88,23,1,32,92,47

%N Sum of squarefree divisors of n that have an even number of prime factors.

%H Antti Karttunen, <a href="/A318674/b318674.txt">Table of n, a(n) for n = 1..65537</a>

%F a(n) = Sum_{d|n} [A008683(d) > 0]*d.

%F a(n) = A048250(n) - A318675(n).

%F For all n >= 1, a(n) <= A318676(n).

%o (PARI) A318674(n) = sumdiv(n,d,(1==moebius(d))*d);

%Y Cf. A048250, A166142, A284118, A291784, A318675, A318676.

%K nonn

%O 1,6

%A _Antti Karttunen_, Sep 04 2018