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A298080
Integers m such that both phi(m) and sigma(m) are coprime to tau(m).
1
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
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
KEYWORD
nonn
AUTHOR
Michel Marcus, Jan 12 2018
STATUS
approved