OFFSET
1,2
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
MATHEMATICA
Do[If[Mod[DivisorSigma[13, n]-EulerPhi[n]^13, n]==0, Print[n]], {n, 1, 10^5}]
PROG
(PARI) isok(n) = !((sigma(n, 13) - eulerphi(n)^13) % n); \\ Michel Marcus, Mar 02 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 09 2000
EXTENSIONS
Definition corrected and more terms from Michel Marcus, Mar 02 2014
STATUS
approved