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A064593
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Nonunitary triply perfect numbers: the sum of the nonunitary divisors of n is 3n; i.e. sigma(n) - usigma(n) = 3n.
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5
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..7.
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CROSSREFS
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Cf. A048146, A064591, A064592, A064594, A064595, A064596.
Sequence in context: A179586 A201557 A061440 * A084304 A178565 A195902
Adjacent sequences: A064590 A064591 A064592 * A064594 A064595 A064596
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KEYWORD
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nonn,hard
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AUTHOR
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Dean Hickerson (dean.hickerson(AT)yahoo.com), Sep 25, 2001
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EXTENSIONS
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There are no others up to 1.6*10^13, but there are at least 20 larger ones, between 87916260096000 and 19424258892617980729341453189120.
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STATUS
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approved
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