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Search: id:A114887
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| A114887 |
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Multiperfect numbers sigma(n)=k*n, which are divisible by the sum of their prime factors without repetition. |
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2
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| 120, 672, 32760, 2178540, 1379454720, 14182439040, 518666803200, 30823866178560, 71065075104190073088, 154345556085770649600, 9186050031556349952000, 680489641226538823680000
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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From a list of about 5000 multiperfect numbers, 38 numbers were found with the property, all having k<=9, the largest was the only one having k=9. A091443 uses sofpr with repetition. Conjecture: the sequence is finite.
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LINKS
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Sven Simon, Table of n, a(n) for n = 1..38 [Conjectured to be complete]
Achim Flammenkamp, List with multiperfect numbers
Eric Weisstein's World of Mathematics, Multiperfect numbers
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EXAMPLE
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a(0) = 120 = 2^3*3*5, sofpr(120) = 2+3+5 = 10.
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CROSSREFS
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Cf. A091443.
Sequence in context: A090216 A113546 A166069 this_sequence A069085 A039688 A005820
Adjacent sequences: A114884 A114885 A114886 this_sequence A114888 A114889 A114890
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KEYWORD
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fini,nonn
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AUTHOR
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Sven Simon (sven-h.simon(AT)t-online.de), Feb 19 2006
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