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 A057627 Number of nonsquarefree numbers not exceeding n. 4

%I

%S 0,0,0,1,1,1,1,2,3,3,3,4,4,4,4,5,5,6,6,7,7,7,7,8,9,9,10,11,11,11,11,

%T 12,12,12,12,13,13,13,13,14,14,14,14,15,16,16,16,17,18,19,19,20,20,21,

%U 21,22,22,22,22,23,23,23,24,25,25,25,25,26,26,26,26,27,27,27,28,29,29,29

%N Number of nonsquarefree numbers not exceeding n.

%C Asymptotic to (1 - 1 / zeta(2)) * n = (1 - 6 / pi^2) * n. - Daniel Forgues, Jan 28 2011

%F a(n)=n-A013928(n)=n-Sum(Moebius(k)^2, k=1, ..n)

%e a(36)=13 because 13 not-squarefree numbers exist which do not exceed 36:{4,8,9,12,16,18,20,24,25,27,28,32,36}. This sequence is different from A013940, albeit the first 35 terms are identical.

%Y Cf. A008683, A013940, A013928, A002321, A028442.

%K nonn

%O 0,8

%A Labos E. (labos(AT)ana.sote.hu), Oct 10 2000

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