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A015771
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Numbers k such that phi(k) | sigma_13(k).
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12
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1, 2, 3, 6, 12, 14, 15, 30, 35, 42, 56, 70, 78, 105, 140, 168, 190, 210, 248, 264, 270, 357, 418, 420, 570, 594, 616, 630, 714, 744, 749, 812, 840, 910, 1045, 1240, 1254, 1485, 1498, 1672, 1848, 2090, 2214, 2247, 2376, 2436, 2568, 2580, 2730
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OFFSET
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1,2
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COMMENTS
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sigma_13(n) is the sum of the 13th powers of the divisors of n.
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LINKS
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FORMULA
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MAPLE
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with(numtheory); a := []: for n from 1 to 3000 do if sigma[13](n) mod phi(n) = 0 then a := [op(a), n]; fi; od: a;
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MATHEMATICA
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Select[Range[3000], Divisible[DivisorSigma[13, #], EulerPhi[#]] &] (* Amiram Eldar, Nov 02 2019 *)
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CROSSREFS
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Cf. A020492, A015759, A015761, A015762, A015763, A015764, A015765, A015766, A015767, A015768, A015769, A015770, A015773, A015774, A094470.
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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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