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%I #12 Jul 08 2024 08:50:17
%S 0,0,0,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,
%T 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,
%U 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,1
%N a(n) = 1 if (2*phi(n)) < n, 0 otherwise, where phi is Euler totient function (A000010).
%C Characteristic function of A054741.
%H Antti Karttunen, <a href="/A323170/b323170.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%t Array[Boole[2*EulerPhi[#] < #] &, 100] (* _Paolo Xausa_, Jul 08 2024 *)
%o (PARI) A323170(n) = ((2*eulerphi(n))<n);
%Y Cf. A000010, A054741, A083254, A318875 (Inverse Möbius transform), A374134.
%K nonn
%O 1
%A _Antti Karttunen_, Jan 05 2019