This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A298080 #13 Aug 08 2020 11:30:11 %S A298080 1,2,4,16,25,64,81,100,121,256,289,484,529,729,841,1024,1156,1296, %T A298080 1600,1681,2116,2209,2401,2809,3025,3364,3481,4096,4624,5041,5184, %U A298080 6400,6724,6889,7225,7921,8464,8836,10201,11236,11449,11664,12100,12769,13225,13456,13924 %N A298080 Integers m such that both phi(m) and sigma(m) are coprime to tau(m). %H A298080 Amiram Eldar, <a href="/A298080/b298080.txt">Table of n, a(n) for n = 1..10000</a> %H A298080 Jean-Marie De Koninck and Imre Kátai, <a href="https://www.emis.de/journals/PIMB/101/9.html">On the coprimality of some arithmetic functions</a>, Publications de l'Institut Mathématique, 2010 87(101):121-128. %t A298080 Select[Range[14000], CoprimeQ[EulerPhi[#], (d = DivisorSigma[0, #])] && CoprimeQ[DivisorSigma[1, #], d] &] (* _Amiram Eldar_, Aug 08 2020 *) %o A298080 (PARI) isok(n) = (gcd(eulerphi(n), numdiv(n))==1) && (gcd(sigma(n), numdiv(n)) == 1); %Y A298080 Intersection of A046678 and A225983. %K A298080 nonn %O A298080 1,2 %A A298080 _Michel Marcus_, Jan 12 2018