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A015771 Numbers k such that phi(k) | sigma_13(k). 12
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
sigma_13(n) is the sum of the 13th powers of the divisors of n.
LINKS
FORMULA
{n: A000010(n) | A013961(n)}. - R. J. Mathar, Sep 21 2017
MAPLE
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;
MATHEMATICA
Select[Range[3000], Divisible[DivisorSigma[13, #], EulerPhi[#]] &] (* Amiram Eldar, Nov 02 2019 *)
CROSSREFS
Sequence in context: A015763 A015769 A015765 * A020492 A110590 A329401
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset corrected by Amiram Eldar, Nov 02 2019
STATUS
approved

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Last modified March 28 16:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)