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%I #20 Jul 09 2022 11:09:34
%S 1,2,4,6,8,9,10,12,16,18,24,32,36,42,44,48,50,54,64,72,81,90,96,100,
%T 108,114,126,128,144,150,162,184,192,198,200,216,234,250,252,256,288,
%U 294,324,378,384,396,400,432,441,450,484,486,504,512,550,558,576,588
%N Numbers k such that k*Sum_{d|k} 1/phi(d) is an integer.
%H Amiram Eldar, <a href="/A069167/b069167.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[600],IntegerQ[#(Total[1/(EulerPhi[Divisors[#]])])]&](* _Harvey P. Dale_, Dec 17 2018 *)
%o (PARI) is(n)=denominator(sumdiv(n,d,1/eulerphi(d))*n)==1 \\ _Charles R Greathouse IV_, Oct 27 2015
%Y Cf. A000010.
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Apr 09 2002
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