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%I #16 Oct 12 2021 14:00:41
%S 4,6,9,10,14,15,16,18,20,22,25,26,27,30,32,34,35,38,39,40,45,46,48,49,
%T 50,51,52,54,55,58,60,62,64,68,70,74,75,78,81,82,85,86,87,90,94,95,96,
%U 98,100,102,104,105,106,110,111,112,115,116,118,119,120,121,122,123,125,128,134,135,136,140,142,143,144,146,148,150,153
%N Composite numbers k such that there are exactly phi(phi(k)) residues modulo k of the maximum order.
%C Composite numbers k such that A111725(k) = A010554(k).
%C Contains as a subsequence the nontrivial prime powers (A246547) except 2^3 = 8.
%H Amiram Eldar, <a href="/A300079/b300079.txt">Table of n, a(n) for n = 1..10000</a>
%t q[n_] := Count[(t = Table[MultiplicativeOrder[k, n], {k, Select[Range[n], CoprimeQ[n, #] &]}]), Max[t]] == EulerPhi[EulerPhi[n]]; Select[Range[150], CompositeQ[#] && q[#] &] (* _Amiram Eldar_, Oct 12 2021 *)
%Y Subsequence of A300064.
%Y Set difference of A002808 and A300065.
%Y Contains A300080 as a subsequence.
%Y Cf. A000010, A002322, A010554, A111725, A246547.
%K nonn
%O 1,1
%A _Max Alekseyev_, Feb 24 2018
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