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%I #11 Sep 23 2012 21:20:46
%S 1,1,1,1,1,2,2,2,2,4,0,2,2,2,4,4,2,6,0,2,4,10,0,4,4,6,0,6,0,8,8,4,8,4,
%T 0,6,6,4,0,8,0,12,8,4,10,22,8,12,8,8,8,12,6,8,8,6,12,28,8,8,8,6,16,8,
%U 8,20,16,10,8,24,8,12,12,8,12,8,8,24,16,18,16,40,8,16,12
%N Number of primitive roots Modd n (see A216321).
%C This sequence coincides with A216321 for all n values from A206551 (cyclic multiplicative Modd n group) and the entry is 0 otherwise (if no primitive root exists, that is, n is from the complementary sequence A206552).
%F a(n) = A216321(n) if n belongs to the sequence A206551 and a(n)=0 if n belongs to A206552.
%e a(8) = phi(phi(2*8)/2) = 2 , with phi = A000010, because 8 = A206551(8).
%e a(12) = 0 because 12 = A206552(1).
%Y Cf. A216321, A046144 (modulo n analog).
%K nonn
%O 1,6
%A _Wolfdieter Lang_, Sep 21 2012
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