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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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4
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120, 672, 32760, 2178540, 1379454720, 14182439040, 518666803200, 30823866178560, 71065075104190073088, 154345556085770649600, 9186050031556349952000, 680489641226538823680000
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OFFSET
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1,1
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COMMENTS
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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 sopfr with repetition.
Conjecture: the sequence is finite.
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LINKS
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EXAMPLE
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a(0) = 120 = 2^3*3*5, sopf(120) = 2+3+5 = 10.
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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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