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A102408
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Harmonic means associated with A090945.
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1
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1, 5, 6, 8, 9, 11, 10, 15, 15, 14, 17, 24, 24, 21, 13, 19, 27, 25, 29, 26, 44, 44, 29, 46, 39, 46, 27, 42, 47, 47, 54, 35, 41, 60, 51, 37, 48, 45, 49, 50, 49, 53, 77, 86, 86, 51, 96, 75, 70, 80, 99, 110, 81, 84, 102, 82, 96, 114, 53, 108, 115, 105, 116, 91
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OFFSET
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1,2
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COMMENTS
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A perfect number N=2^(p-1)*M(p) (=A000396), {with associated Mersenne prime M(p)=2^p -1 (=A000668)}, has harmonic mean N*tau(N)/sigma(N) = p (=A000043).
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LINKS
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FORMULA
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PROG
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(PARI) lista(nn) = {for (n=1, nn, ab = sigma(n)/n; hm = numdiv(n)/ab; if ((type(hm) == "t_INT") && (ab != 2), print1(hm, ", ")); ); } \\ Michel Marcus, Oct 26 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(1)=1 as well as a(29)=47 inserted and more terms added by Michel Marcus, Oct 26 2013
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STATUS
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approved
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