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Numbers n such that sigma(n)/phi(n) = 36/25.
2

%I #7 Jul 14 2012 11:32:31

%S 5797,10153,20377,50953,383719,405449,446039,486421,608399,973709,

%T 1321529,1521311,3086369,3228511,3451877,3529813,3859513,4552373,

%U 4767721,5827679,6194321,6479599,6724039,6927893,7038241,7919197,11696111,15893773,16894141,16924873

%N Numbers n such that sigma(n)/phi(n) = 36/25.

%C A subsequence of A011257. See A164646-A164650 for related sequences.

%H Donovan Johnson, <a href="/A164649/b164649.txt">Table of n, a(n) for n = 1..1000</a>

%o (PARI) for( n=1,1e7, sigma(n)==36/25*eulerphi(n) && print1(n","))

%Y Cf. A000010 (=phi), A000203 (=sigma), A068390 (sigma/phi=4), A163667 (sigma/phi=9), A164646-A164650.

%K nonn

%O 1,1

%A _M. F. Hasler_, Aug 22 2009

%E More terms from _Sean A. Irvine_, May 17 2010