A298080 Integers m such that both phi(m) and sigma(m) are coprime to tau(m).

1, 2, 4, 16, 25, 64, 81, 100, 121, 256, 289, 484, 529, 729, 841, 1024, 1156, 1296, 1600, 1681, 2116, 2209, 2401, 2809, 3025, 3364, 3481, 4096, 4624, 5041, 5184, 6400, 6724, 6889, 7225, 7921, 8464, 8836, 10201, 11236, 11449, 11664, 12100, 12769, 13225, 13456, 13924

Offset: 1

Author

Michel Marcus, Jan 12 2018

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Jean-Marie De Koninck and Imre Kátai, On the coprimality of some arithmetic functions, Publications de l'Institut Mathématique, 2010 87(101):121-128.

Crossrefs

Intersection of A046678 and A225983.

Programs

Mathematica

Select[Range[14000], CoprimeQ[EulerPhi[#], (d = DivisorSigma[0, #])] && CoprimeQ[DivisorSigma[1, #], d] &] (* Amiram Eldar, Aug 08 2020 *)

PARI

isok(n) = (gcd(eulerphi(n), numdiv(n))==1) && (gcd(sigma(n), numdiv(n)) == 1);