A015768 Numbers k such that phi(k) | sigma_10(k).

1, 2, 3, 6, 22, 33, 66, 166, 250, 375, 498, 750, 1506, 1826, 5478, 8250, 10375, 10873, 16566, 17762, 20750, 21746, 31125, 32619, 41666, 53286, 62250, 62499, 65238, 98250, 110066, 119603, 124998, 177153, 195382, 228250, 239206

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn

Comments

sigma_10(k) = A013958(k) is the sum of the 10th powers of the divisors of k.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..623

Crossrefs

Cf. A000010, A013958.

Cf. A020492, A015759, A015761, A015762, A015763, A015764, A015765, A015766, A015767, A015769, A015770, A015771, A015773, A015774, A094470.

Programs

Magma

[k:k in [1..240000]| IsIntegral(DivisorSigma(10,k)/EulerPhi(k))]; // Marius A. Burtea, Nov 06 2019

Mathematica

Select[Range[240000], Divisible[DivisorSigma[10, #], EulerPhi[#]] &] (* Amiram Eldar, Nov 06 2019 *)