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

1,2

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.

Mathematica

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

Prog

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

Crossrefs

Intersection of A046678 and A225983.

Sequence in context: A358000 A275674 A225983 * A292369 A357917 A153665

Adjacent sequences: A298077 A298078 A298079 * A298081 A298082 A298083

Keyword

nonn

Author

Michel Marcus, Jan 12 2018

Status

approved