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Numbers n such that sigma(n)^2>4*sigma_2(n) where sigma_2(n) is the sum of squares over the divisors of n.
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%I #10 Dec 27 2015 09:45:14

%S 24,36,48,60,72,84,90,96,108,120,126,132,140,144,150,156,160,168,180,

%T 192,204,210,216,228,240,252,264,270,276,280,288,300,312,320,324,330,

%U 336,360,378,384,390,396,400,408,420,432,440,450,456,462,468,480,504

%N Numbers n such that sigma(n)^2>4*sigma_2(n) where sigma_2(n) is the sum of squares over the divisors of n.

%H Harvey P. Dale, <a href="/A067766/b067766.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[600],DivisorSigma[1,#]^2>4*DivisorSigma[2,#]&] (* _Harvey P. Dale_, Dec 27 2015 *)

%o (PARI) for(n=1,1000,if(sigma(n)^2>4*sumdiv(n,k,k^2),print1(n,",")))

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Apr 04 2002