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A141546
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Numbers whose abundance is 14.
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3
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OFFSET
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1,1
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COMMENTS
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Any term x of this sequence can be combined with any term y of A141550 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable. - Timothy L. Tiffin, Sep 13 2016
Every number of the form 2^(j-1)*(2^j - 15), where 2^j - 15 is prime, is a term. - Jon E. Schoenfield, Jun 02 2019
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LINKS
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EXAMPLE
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a(1) = 272, since sigma(272) - 2*272 = 558 - 544 = 14. - Timothy L. Tiffin, Sep 13 2016
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MATHEMATICA
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lst={}; Do[If[n==Plus@@Divisors[n]-n-14, AppendTo[lst, n]], {n, 10^4}]; Print[lst];
lst = {}; Do[ If[2 n + 14 == DivisorSigma[1, n], AppendTo[lst, n]], {n, 2 10^8, 2}]; lst (* Robert G. Wilson v, Aug 17 2008 *)
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PROG
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(PARI) isok(n) = sigma(n) - 2*n == 14; \\ Michel Marcus, Mar 20 2015
(Magma) [n: n in [1..10^8] | SumOfDivisors(n)- 2*n eq 14]; // Vincenzo Librandi, Mar 20 2015
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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