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A104039 Number of primitive roots modulo prime(n)^2, where prime(n) is n-th prime. 2
1, 2, 8, 12, 40, 48, 128, 108, 220, 336, 240, 432, 640, 504, 1012, 1248, 1624, 960, 1320, 1680, 1728, 1872, 3280, 3520, 3072, 4000, 3264, 5512, 3888, 5376, 4536, 6240, 8704, 6072, 10656, 6000, 7488, 8748, 13612, 14448, 15664, 8640, 13680, 12288, 16464 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

I. Niven, H. S. Zuckerman & H. L. Montgomery, An Introduction to the Theory of Numbers, 5th Ed., p. 102, John Wiley, NY, 1991.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = (prime(n) - 1)*phi((prime(n) - 1)) = A006093(n)*A000010(A006093(n)) = A006093(n)*A008330(n).

MAPLE

with(numtheory): for p from 1 to 100 do printf(`%d, `, (ithprime(p)-1)*phi(ithprime(p)-1)) od: # James A. Sellers, Apr 10 2005

MATHEMATICA

Table[(Prime[n] - 1) EulerPhi[(Prime[n] - 1)], {n, 50}] (* Vincenzo Librandi, Aug 18 2017

PROG

(MAGMA) [(NthPrime(n)-1)*EulerPhi((NthPrime(n)-1)): n in [1..50]]; // Vincenzo Librandi, Aug 18 2017

CROSSREFS

Sequence in context: A285551 A135443 A143231 * A280092 A083546 A013190

Adjacent sequences:  A104036 A104037 A104038 * A104040 A104041 A104042

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Mar 31 2005

EXTENSIONS

More terms from James A. Sellers, Apr 10 2005

STATUS

approved

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Last modified August 9 13:57 EDT 2020. Contains 336323 sequences. (Running on oeis4.)