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A067718
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Numbers k such that sigma(2^k+1) == 0 (mod k).
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0
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1, 2, 6, 12, 24, 36, 42, 70, 126, 132, 144, 168, 210, 225, 252, 336, 344, 378, 385, 396, 462, 504, 528, 546, 560, 561, 576, 627, 630, 660, 672, 693, 714, 798, 896, 924, 930, 945, 960, 1001, 1008, 1012, 1032, 1050
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Select[Range[150], Divisible[DivisorSigma[1, 2^# + 1], #] &] (* Amiram Eldar, Nov 28 2020 *)
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PROG
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(PARI) for(n=1, 260, if(sigma(2^n+1)%n==0, print1(n, ", "))) \\ Klaus Brockhaus, Apr 13 2005
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CROSSREFS
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KEYWORD
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nonn,hard,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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