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A067708 Numbers n such that phi(sigma(n)) = 5*phi(n). 0

%I

%S 336,1008,1680,4368,5040,12432,13104,21840,24528,37296,52752,57792,

%T 62160,64848,65520,73584,93072,105168,122640,128520,133392,141456,

%U 153552,158256,161616,167700,173376,181776,186480,194544,205968,222096,226128,246288,254352

%N Numbers n such that phi(sigma(n)) = 5*phi(n).

%t Select[Range[260000],EulerPhi[DivisorSigma[1,#]]==5*EulerPhi[#]&] (* _Harvey P. Dale_, Jul 11 2018 *)

%o (PARI) isok(n) = eulerphi(sigma(n)) == 5*eulerphi(n); \\ _Michel Marcus_, Nov 22 2013

%Y Cf. A067706.

%K nonn

%O 1,1

%A _Benoit Cloitre_, Feb 05 2002

%E More terms from _Michel Marcus_, Nov 22 2013

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Last modified March 25 22:28 EDT 2019. Contains 321477 sequences. (Running on oeis4.)