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%I A063469 #14 Dec 15 2017 17:35:21
%S A063469 7,21,26,56,70,78,108,126,168,210
%N A063469 Numbers n such that tau(n)*3 = phi(n).
%C A063469 "phi(n)=k*Tau[n] has at most finitely many solutions for any constant k or even for slowly increasing functions like k(n)=n^(epsilon)." - _Labos Elemer_, Jul 20 2001
%t A063469 Select[Range[300],3DivisorSigma[0,#]==EulerPhi[#]&] (* _Harvey P. Dale_, Sep 15 2016 *)
%o A063469 (PARI) for(n=1,10^7, if(3*numdiv(n)==eulerphi(n),print(n)))
%Y A063469 Cf. A062516.
%Y A063469 Cf. A112954, A020488, A063470.
%K A063469 fini,full,nonn
%O A063469 1,1
%A A063469 _Jason Earls_, Jul 26 2001
%E A063469 "full" keyword from _Max Alekseyev_, Mar 01 2010

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