A216322 Number of primitive roots Modd n (see A216321).

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, 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, 8, 20, 16, 10, 8, 24, 8, 12, 12, 8, 12, 8, 8, 24, 16, 18, 16, 40, 8, 16, 12

Offset: 1

Author

Wolfdieter Lang, Sep 21 2012

Keywords

• nonn

Comments

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).

Examples

			a(8) = phi(phi(2*8)/2) = 2 , with phi = A000010, because 8 = A206551(8).
a(12) = 0 because 12 = A206552(1).
		

Crossrefs

Cf. A216321, A046144 (modulo n analog).

Formula

a(n) = A216321(n) if n belongs to the sequence A206551 and a(n)=0 if n belongs to A206552.