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A015847
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Numbers k such that phi(k + 4) | sigma(k) for k not congruent to 0 (mod 3).
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1
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5, 10, 14, 22, 34, 35, 38, 58, 70, 82, 95, 110, 118, 140, 142, 143, 191, 202, 214, 224, 230, 274, 298, 308, 358, 374, 376, 382, 394, 454, 478, 538, 562, 590, 598, 616, 620, 622, 623, 694, 728, 838, 862, 920, 922, 1012, 1042, 1121, 1138, 1198
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[1000], Mod[#, 3] > 0 && Divisible[DivisorSigma[1, #], EulerPhi[#+4]] &] (* Amiram Eldar, Dec 13 2018 *)
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PROG
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(Magma) [n: n in [1..1000] | n mod 3 ne 0 and DivisorSigma(1, n) mod EulerPhi(n+4) eq 0]; // G. C. Greubel, Dec 13 2018
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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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