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A023048 Smallest prime having least positive primitive root n, or 0 if no such prime exists. 6
2, 3, 7, 0, 23, 41, 71, 0, 0, 313, 643, 4111, 457, 1031, 439, 0, 311, 53173, 191, 107227, 409, 3361, 2161, 533821, 0, 12391, 0, 133321, 15791, 124153, 5881, 0, 268969, 48889, 64609, 0, 36721, 55441, 166031, 1373989, 156601, 2494381, 95471, 71761, 95525767 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

a(n) = 0 iff n is a prime power p^k, k >= 2 (i.e. a member of A001592).

REFERENCES

A. E. Western and J. C. P. Miller, Tables of Indices and Primitive Roots. Royal Society Mathematical Tables, Vol. 9, Cambridge Univ. Press, 1968, p. XLIV.

LINKS

N. J. A. Sloane, Table of n, a(n) for n=1..107 (from the web page of Tomas Oliveira e Silva)

Wouter Meeussen, Smallest Primes with Specified Least Primitive Root

Tomas Oliveira e Silva, Least primitive root of prime numbers

Index entries for primes by primitive root

EXAMPLE

a(2) = 3, since 3 has 2 as smallest positive primitive root and no prime p < 3 has 2 as smallest positive primitive root. a(24) = 533821, since prime 533821 has 24 as smallest positive primitive root and no prime p < 533821 has 24 as smallest positive primitive root.

MATHEMATICA

(* first load package *) << NumberTheory`NumberTheoryFunctions` (* then do *) t = Table[0, {100}]; Do[a = PrimitiveRoot@Prime@n; If[a < 101 && t[[a]] == 0, t[[a]] = n], {n, 10^6}]; Unprotect[Prime]; Prime[0] = 0; Prime@t; Clear[Prime]; Protect[Prime] (from Robert G. Wilson v (rgwv(at)rgwv.com), Dec 15 2005)

CROSSREFS

Cf. A001122-A001126, A061323-A061335, A061730-A061741. Index of primes: A066529.

For records see A133433. See A133432 for a version without the 0's.

Sequence in context: A201363 A117024 A203143 * A083521 A104691 A011160

Adjacent sequences:  A023045 A023046 A023047 * A023049 A023050 A023051

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

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Last modified February 15 19:15 EST 2012. Contains 205852 sequences.