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A056097
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Numbers n such that phi(n) + 1 | sigma(n).
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3
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6, 8, 30, 36, 44, 156, 696, 944, 2800, 2928, 3600, 6660, 16064, 195456, 260864, 784128, 4189184, 12573696, 201289728, 17179541504, 274876596224, 824631361536
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OFFSET
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1,1
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COMMENTS
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Contains 2^k(2^(k+2)-5) where 2^(k+2)-5 is prime; contains 2^k*3*(2^(k+2)-3) where 2^(k+2)-3 is prime; complete up to 5000000000. - David W. Wilson, May 16 2001
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LINKS
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MATHEMATICA
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Do[If[Mod[DivisorSigma[1, n], EulerPhi[n]+1]==0, Print[n]], {n, 1, 10^7}]
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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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