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

1, 2, 3, 6, 19689, 39378

Offset

1,2

Comments

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

sigma(16j+8,x)/phi(x) is 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

Links

Table of n, a(n) for n=1..6.

Mathematica

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

Crossrefs

Cf. A015759, A015762, A015770, A091285.

Sequence in context: A351328 A367897 A094469 * A295484 A365621 A117024

Adjacent sequences: A015763 A015764 A015765 * A015767 A015768 A015769

Keyword

nonn

Author

Robert G. Wilson v

Status

approved