A216322 - OEIS

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

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OFFSET

1,6

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).

LINKS

Table of n, a(n) for n=1..85.

FORMULA

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

EXAMPLE

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).

Sequence in context: A078228 A119762 A153667 * A335383 A125914 A086668

Adjacent sequences: A216319 A216320 A216321 * A216323 A216324 A216325

KEYWORD

nonn

AUTHOR

Wolfdieter Lang, Sep 21 2012

STATUS

approved