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A348709
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Number of squarefree integers with an even number of prime factors <= 10^n.
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1
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1, 3, 31, 305, 3030, 30373, 304069, 3040164, 30397311, 303963451, 3039618610, 30396311212, 303963582320, 3039635808938, 30396354655186, 303963549318865, 3039635507672484, 30396355081786770, 303963550903632005, 3039635509720135531, 30396355092931863204, 303963550925315375170
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OFFSET
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0,2
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COMMENTS
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a(n) is the number of integers k <= 10^n with mu(k)=1 where mu(k) is the Möbius function.
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LINKS
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Table of n, a(n) for n=0..21.
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FORMULA
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a(n) = (A071172(n) + A084237(n)) / 2.
Lim_{n->oo} a(n)/10^n = 3/Pi^2 (A104141).
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EXAMPLE
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a(1) = 3 because there are 3 squarefree integers with an even number of prime factors <= 10: 1, 6, 10.
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MATHEMATICA
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Table[Length@Select[Range[10^n], MoebiusMu@#==1&], {n, 0, 6}]
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CROSSREFS
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Cf. A071172, A084237, A008683, A030229, A104141, A348708.
Sequence in context: A236957 A112425 A144579 * A220997 A222094 A069589
Adjacent sequences: A348706 A348707 A348708 * A348710 A348711 A348712
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KEYWORD
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nonn
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AUTHOR
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Giorgos Kalogeropoulos, Oct 30 2021
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STATUS
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approved
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