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%I #17 May 13 2013 01:49:41
%S 9,21,65,1729,3201,4125441
%N Composite numbers n such that phi(n) divides 3n - 3.
%C Next term > 10^9.
%t t={};Do[If[PrimeQ[n]==False&&IntegerQ[(n-1)*3/EulerPhi[n]],Print[n];AppendTo[t,n]],{n,2,10^5}];t
%o (PARI) p=3;forprime(q=5,1e8,forstep(n=p\4*4,q-1,4,if((3*n-3)%eulerphi(n)==0,print1(n", ")));p=q) \\ _Charles R Greathouse IV_, Jul 24 2011
%K nonn
%O 1,1
%A _José María Grau Ribas_, Jul 20 2011
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