A138304 Number of prime primitive roots of prime(n).

0, 1, 2, 2, 2, 3, 4, 3, 5, 4, 4, 5, 6, 4, 9, 6, 8, 6, 7, 9, 8, 8, 11, 12, 11, 12, 7, 12, 9, 16, 11, 11, 17, 9, 18, 6, 11, 17, 23, 18, 20, 13, 20, 16, 19, 13, 12, 15, 24, 20, 28, 24, 17, 23, 28, 32, 29, 15, 24, 23, 13, 31, 20, 32, 23, 28, 15, 21, 32, 22, 28, 42, 27, 29, 21, 43, 40, 27

Offset: 1

Author

T. D. Noe, Mar 14 2008

Keywords

• nonn

Examples

			a(5)=2 because the primitive roots of 11 are 2, 6, 7 and 8, two of which are prime.
		

Links

• T. D. Noe, Table of n, a(n) for n=1..10000

Crossrefs

Cf. A060749 (primitive roots), A138304 (prime primitive roots).

Programs

Mathematica

Table[p=Prime[n]; g=Select[Prime[Range[n-1]], MultiplicativeOrder[ #,p]==p-1&]; Length[g], {n,100}]