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A278337
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Composite numbers n such that the sum of proper divisors of n divides 2^n+1.
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0
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15, 45, 99, 735, 1221, 1645, 1725, 1925, 2871, 4047, 8667, 13311, 16461, 19647, 21285, 27797, 39861, 52215, 52965, 65637, 67479, 74781, 106327, 124215, 126975, 155511, 181917, 240397, 244839, 257951, 315695, 344175, 412863, 442417, 445215, 449493, 707859, 1362079
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OFFSET
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1,1
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COMMENTS
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Are all terms odd? There are no even terms < 2*10^12.
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LINKS
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MAPLE
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select(n -> not isprime(n) and 2 &^n + 1 mod (numtheory:-sigma(n)-n) = 0, [$2..10^6]);
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PROG
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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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