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%I A374134 #21 Jul 08 2024 08:52:37
%S A374134 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
%T A374134 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,
%U A374134 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1
%N A374134 a(n) = 1 if 2*phi(n) > n, otherwise 0, where phi is Euler's totient function phi, A000010.
%H A374134 Antti Karttunen, <a href="/A374134/b374134.txt">Table of n, a(n) for n = 1..100000</a>
%H A374134 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F A374134 a(n) = [A083254(n) > 0], where [ ] is the Iverson bracket.
%F A374134 a(2*k) = 0 for k >= 1. - _Paolo Xausa_, Jul 08 2024
%t A374134 Array[Boole[2*EulerPhi[#] > #] &, 100] (* _Paolo Xausa_, Jul 08 2024 *)
%o A374134 (PARI) A374134(n) = ((2*eulerphi(n))>n);
%Y A374134 Characteristic function of A089684.
%Y A374134 Cf. A000010, A083254, A318874 (inverse Möbius transform), A323170.
%Y A374134 Differs from A000035 first at n=105, where a(105) = 0, while A000035(105) = 1.
%Y A374134 Differs from A374136 first at n=255, where a(255) = 1, while A374136(255) = 0.
%K A374134 nonn
%O A374134 1
%A A374134 _Antti Karttunen_, Jul 06 2024

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