A094468 Numbers k such that sum of 9th powers of divisors of k is divisible by the square of Euler-phi of k.

1, 2, 3, 6, 14, 42, 3810, 26670, 34162, 41256, 48546, 87096, 102486, 131934, 210482, 288792, 315723, 318990, 430122, 529848, 609672, 631446, 979830, 1023366, 1203960, 1473374, 1683126, 1920699, 2210061, 2241934, 2506086, 2549610

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..420

Formula

A013957(k)/A000010(k)^2 is integer.

Mathematica

Select[Range[2600000], Divisible[Total[Divisors[#]^9], (EulerPhi[#])^2]&]  (* Harvey P. Dale, Mar 04 2011 *)

Prog

(PARI) for(n=1, 10000000, if(Mod(sigma(n, 9), eulerphi(n)^2)==0, print1(n, ", "))) \\ C. Ronaldo

Crossrefs

Cf. A015763, A000010, A091285, A013957.

Sequence in context: A188775 A015892 A056569 * A091285 A109459 A118986

Adjacent sequences: A094465 A094466 A094467 * A094469 A094470 A094471

Keyword

nonn

Author

Labos Elemer, May 19 2004

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 18 2005

Status

approved