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%I #12 Apr 01 2018 20:08:40
%S 760,11020,18088,21112,58206,65262,71630,100280,123424,142688,262276,
%T 303212,332710,630344,679070,761390,1265096,1369120,1454060,1454260,
%U 1462552,1704794,2185750,2386664,2627548,2783872,2786056,2909380,2927848,5207680,5289220
%N Numbers n such that sigma(n)/phi(n) = 25/4, where sigma = A000203, phi = A000010.
%C A subsequence of A011257. Contains the product m*n of relatively prime (gcd(m,n)=1) terms (m,n) in A068390 x A164648 and in A164646 x A165630.
%H Donovan Johnson, <a href="/A165629/b165629.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[5300000],4*DivisorSigma[1,#]==25*EulerPhi[#]&] (* _Harvey P. Dale_, May 09 2012 *)
%o (PARI) for( i=1,1e9, sigma(i)*4-25*eulerphi(i) || print1(i", "))
%K nonn
%O 1,1
%A _Farideh Firoozbakht_ and _M. F. Hasler_, Sep 23 2009
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