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A081756
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Numbers n such that there is a proper divisor d of n satisfying sigma(d)=n.
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5
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1, 12, 56, 360, 992, 2016, 16256, 120960, 131040, 1571328, 8714160, 67100672, 94279680, 182131200, 571963392, 1379454720, 4428914688, 5517818880, 17179738112, 70912195200, 153003540480, 159991977600, 175445913600, 265734881280, 274877382656, 612014161920
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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kmax = 10^12;
A007691 = Cases[Import["https://oeis.org/A007691/b007691.txt", "Table"], {_, _}][[All, 2]];
A054030 = Cases[Import["https://oeis.org/A054030/b054030.txt", "Table"], {_, _}][[All, 2]];
okQ[n_] := AnyTrue[Most[Divisors[n]], DivisorSigma[1, #] == n&];
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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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