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%I #10 Sep 28 2018 11:29:55
%S 1,1,2,2,4,2,4,4,4,8,8,16,8,8,8,16,16,16,16,32,16,32,32,32,64,32,32,
%T 32,64,64,64,64,64,64,64,128,128,256,128,128,128,128,128,128,128,256,
%U 256,256,256,256,256,512,256,256,256,512,512,512,512,1024,512,512,512,512
%N a(n) = phi(A003401(n)).
%C All terms are powers of 2. - _Jianing Song_, Sep 28 2018
%t Do[If[IntegerQ[Log[2, EulerPhi[n]]], Print[n];ta[[u]]=n;u=u+1], {n, 1, 10000}] EulerPhi[ta]
%o (PARI) for(n=1, 1000, my(i=eulerphi(n)); if(omega(2*i)==1, print1(i, “, “))) \\ _Jianing Song_, Sep 28 2018
%Y Cf. A000010, A003401.
%K nonn
%O 1,3
%A _Labos Elemer_, Jun 02 2004
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