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%I #4 Mar 30 2012 17:22:47
%S 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,
%T 11,17,9,18,6,11,17,23,18,20,13,20,16,19,13,12,15,24,20,28,24,17,23,
%U 28,32,29,15,24,23,13,31,20,32,23,28,15,21,32,22,28,42,27,29,21,43,40,27
%N Number of prime primitive roots of prime(n).
%H T. D. Noe, <a href="/A138304/b138304.txt">Table of n, a(n) for n=1..10000</a>
%e a(5)=2 because the primitive roots of 11 are 2, 6, 7 and 8, two of which are prime.
%t Table[p=Prime[n]; g=Select[Prime[Range[n-1]], MultiplicativeOrder[ #,p]==p-1&]; Length[g], {n,100}]
%Y Cf. A060749 (primitive roots), A138304 (prime primitive roots).
%K nonn
%O 1,3
%A _T. D. Noe_, Mar 14 2008
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