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A058073
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Numbers k such that sigma(k+1) divides sigma(k), where sigma(k) is the sum of positive divisors of k.
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9
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12, 14, 70, 88, 180, 204, 206, 220, 957, 1334, 1364, 1634, 1750, 1888, 2685, 2958, 2974, 4364, 8142, 8632, 9114, 12000, 14664, 14841, 18414, 18762, 18873, 19358, 20118, 20145, 20712, 24957, 25194, 30996, 33998, 36566, 42818, 45520, 47940
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OFFSET
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1,1
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COMMENTS
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The quotient (sigma(k)/sigma(k+1)) is equal to 1, 2, 3 or 4 for the first 5000 terms. - Donovan Johnson, Oct 21 2012
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LINKS
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EXAMPLE
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12 is included because sigma(13) = 14 divides sigma(12) = 28.
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MATHEMATICA
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Select[Range[50000], Mod[DivisorSigma[1, # ], DivisorSigma[1, # + 1]] == 0 &]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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