A015766 Numbers k such that phi(k) | sigma_8(k).

1, 2, 3, 6, 19689, 39378

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn
• more

Comments

sigma_8(n) is the sum of the 8th powers of the divisors of n.

sigma(16j+8,x)/phi(x) is an integer for j = 0, ..., 500 and 6 actual terms of this sequence. Compare to A015759, A015762, A015770 and A091285. - Labos Elemer, May 27 2004

No additional terms up to 5 million. - Harvey P. Dale, Jan 31 2016

Crossrefs

Cf. A015759, A015762, A015770, A091285.

Programs

Mathematica

Select[Range[40000],Divisible[DivisorSigma[8,#],EulerPhi[#]]&] (* Harvey P. Dale, Jan 31 2016 *)