%I A091286
%S A091286 15,85,259,295,391,589,799,1111,1717,3193,4171,4369,12361,17473,23533,
%T A091286 25429,28243,31351,34477,36181,41407,47989,51143,52537,58103,65641,
%U A091286 68377,69541,69919,70453,72619,81121,83131,83767,85069,91759
%N A091286 Numbers n such that Sigma[3,n] is divisible by square of cototient of 
               n, while n is not a prime number.
%e A091286 n=15: cototient[15]=7,sigma[3,15]=3528=72.49
%t A091286 Do[s=DivisorSigma[3, n]/(n-EulerPhi[n])^2; If[IntegerQ[s]&&!PrimeQ[n], 
               Print[n]], {n, 1, 100000}]
%Y A091286 Cf. A091285.
%Y A091286 Sequence in context: A020136 A067401 A160599 this_sequence A064058 A138322 
               A164541
%Y A091286 Adjacent sequences: A091283 A091284 A091285 this_sequence A091287 A091288 
               A091289
%K A091286 nonn
%O A091286 1,1
%A A091286 Labos E. (labos(AT)ana.sote.hu), Feb 03 2004