Search: a348709 -id:a348709
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A348708
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Number of squarefree integers with an odd number of prime factors <= 10^n.
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+10
1
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0, 4, 30, 303, 3053, 30421, 303857, 3039127, 30395383, 303963673, 3039652332, 30396399068, 303963519954, 3039635209356, 30396355530761, 303963552535238, 3039635510867921, 30396355103617024, 303963550950390745, 3039635508820145344, 30396355092470750098, 303963550928711270447
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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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FORMULA
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Lim_{n->oo} a(n)/10^n = 3/Pi^2 (A104141).
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EXAMPLE
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a(1) = 4 because there are 4 squarefree integers with an odd number of prime factors <= 10: 2, 3, 5, 7.
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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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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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