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 A138304 Number of prime primitive roots of prime(n). 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS T. D. Noe, Table of n, a(n) for n=1..10000 EXAMPLE a(5)=2 because the primitive roots of 11 are 2, 6, 7 and 8, two of which are prime. MATHEMATICA Table[p=Prime[n]; g=Select[Prime[Range[n-1]], MultiplicativeOrder[ #, p]==p-1&]; Length[g], {n, 100}] CROSSREFS Cf. A060749 (primitive roots), A138304 (prime primitive roots). Sequence in context: A112184 A112213 A085755 * A054860 A098745 A029158 Adjacent sequences:  A138301 A138302 A138303 * A138305 A138306 A138307 KEYWORD nonn AUTHOR T. D. Noe, Mar 14 2008 STATUS approved

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