A055707 Numbers k such that k | sigma_13(k) - phi(k)^13.

1, 2, 12, 34, 42, 90, 170, 198, 402, 434, 456, 482, 494, 2046, 4086, 4518, 7520, 7605, 8622, 9632, 10924, 28280, 51570, 51714, 74124, 77724, 100172, 139653, 143136, 176760, 294588, 399980, 471826, 675356, 690534, 1358360, 1577696, 2089074, 2121940, 2136256

Offset: 1

Author

Robert G. Wilson v, Jun 09 2000

Keywords

• nonn

Comments

sigma_13(k) is the sum of the 13th powers of the divisors of k (A013961).

Links

• Amiram Eldar, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A000010, A013961.

Programs

Mathematica

Do[If[Mod[DivisorSigma[13, n]-EulerPhi[n]^13, n]==0, Print[n]], {n, 1, 10^5}]

PARI

isok(n) = !((sigma(n, 13) - eulerphi(n)^13) % n); \\ Michel Marcus, Mar 02 2014

Extensions

Definition corrected and more terms from Michel Marcus, Mar 02 2014