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%I #11 Jun 24 2014 01:08:21
%S 121679,1043909,2350171,2918263,3396103,3566807,3688067,4019467,
%T 4562827,5963407,7300697,7485979,7853933,8103301,8364151,9237779,
%U 9514213,9638527,10531123,11094619,11384447,12721937,13576267
%N Numbers n such that sigma(phi(n))/sigma(n) = 4.
%C Subsequence of A066881. - _R. J. Mathar_, Sep 30 2008
%H Donovan Johnson, <a href="/A067384/b067384.txt">Table of n, a(n) for n = 1..500</a>
%t For[ n=1, True, n++, If[ DivisorSigma[ 1, EulerPhi[ n ] ]/DivisorSigma[ 1, n ]==4, Print[ n ] ] ]
%o (PARI) is(n)=sigma(phi(n=factor(n)))/sigma(n)==4 \\ _Charles R Greathouse IV_, Nov 27 2013
%Y Cf. A033631, A066831, A067382, A067383, A067385, A197952.
%K nonn
%O 1,1
%A _Dean Hickerson_, Jan 20 2002
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