A093038 - OEIS

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

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OFFSET

1,2

COMMENTS

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

LINKS

FORMULA

A001160(n)/A000010(n)^2 is 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

KEYWORD

nonn,more

AUTHOR

Labos Elemer, May 19 2004

EXTENSIONS

a(9) from Amiram Eldar, Mar 07 2020

STATUS

approved