A094469 Numbers k such that sum of 11th powers of divisors of k is divisible by the square of Euler-phi of k.

1, 2, 3, 6, 1645, 3290, 4935, 9870, 3831674, 11495022, 346014339, 692028678

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Formula

A013959(k)/A000010(k)^2 is integer.

Mathematica

Do[ If[ Mod[ DivisorSigma[11, n], EulerPhi[n]^2] == 0, Print[n]], {n, 10^7}] (* Robert G. Wilson v, May 23 2004 *)

Prog

(PARI) isok(k) = (sigma(k, 11) % eulerphi(k)^2) == 0; \\ Michel Marcus, Mar 07 2020

Crossrefs

Cf. A000010, A013959, A015763, A091285.

Sequence in context: A093038 A351328 A367897 * A015766 A295484 A365621

Adjacent sequences: A094466 A094467 A094468 * A094470 A094471 A094472

Keyword

nonn,more

Author

Labos Elemer, May 19 2004

Extensions

a(9) from Robert G. Wilson v, May 23 2004

a(10) from Labos Elemer, May 26 2004

a(6) corrected and a(11)-a(12) added by Amiram Eldar, Mar 07 2020

Status

approved