A093038 Numbers k such that sum of 5th powers of divisors of k is divisible by the square of Euler-phi of k.

1, 2, 3, 6, 322, 966, 473732, 1420296, 6655780894

Offset

1,2

Comments

No more terms through 10^9. - Ryan Propper, Jan 09 2007

Links

Table of n, a(n) for n=1..9.

Formula

A001160(k)/A000010(k)^2 is an integer.

Mathematica

Do[ If[ Mod[ DivisorSigma[5, n], EulerPhi[n]^2] == 0, Print[n]], {n, 10^7}] (* Robert G. Wilson v, May 23 2004 *)

Prog

(PARI) isok(k) = (sigma(k, 5) % eulerphi(k)^2) == 0; \\ Michel Marcus, Mar 07 2020

Crossrefs

Cf. A000010, A015763, A091285.

Sequence in context: A297624 A015762 A015770 * A351328 A367897 A094469

Adjacent sequences: A093035 A093036 A093037 * A093039 A093040 A093041

Keyword

nonn,more,changed

Author

Labos Elemer, May 19 2004

Extensions

a(9) from Amiram Eldar, Mar 07 2020

Status

approved