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A141643
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Numbers n such that sigma(n)/n = 5/2.
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9
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OFFSET
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1,1
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COMMENTS
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There are no other terms through 2^34. - Walter Nissen, Apr 17 2009
No more terms below 10^12. - Jud McCranie, Aug 30 2013
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LINKS
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Table of n, a(n) for n=1..3.
G. P. Michon, Multiperfect and hemiperfect numbers
Walter Nissen, Abundancy : Some Resources
Walter Nissen, Abundancy : Some Resources
Walter Nissen, Primitive Friendly Pairs with friends < 2^34 with denom < 20000
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MATHEMATICA
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Select[Range[100000], DivisorSigma[1, #]/# == 5/2 &] (* Robert Price, Apr 03 2019 *)
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PROG
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(PARI) isok(n) = sigma(n, -1) == 5/2; \\ Michel Marcus, Apr 04 2019
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CROSSREFS
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Cf. A055153, A141645, A159271, A160678.
Sequence in context: A255322 A319900 A172803 * A275026 A297424 A013910
Adjacent sequences: A141640 A141641 A141642 * A141644 A141645 A141646
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KEYWORD
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nonn,more,bref
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AUTHOR
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Yasutoshi Kohmoto, May 10 2008
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EXTENSIONS
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Definition rewritten by M. F. Hasler, May 10 2008
First three terms confirmed by Ray Chandler, Sep 18 2008
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STATUS
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approved
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