A122028 - OEIS

A122028

Least positive prime primitive root of n-th prime.

3, 2, 2, 3, 2, 2, 3, 2, 5, 2, 3, 2, 7, 3, 5, 2, 2, 2, 2, 7, 5, 3, 2, 3, 5, 2, 5, 2, 11, 3, 3, 2, 3, 2, 2, 7, 5, 2, 5, 2, 2, 2, 19, 5, 2, 3, 2, 3, 2, 7, 3, 7, 7, 11, 3, 5, 2, 43, 5, 3, 3, 2, 5, 17, 17, 2, 3, 19, 2, 2, 3, 7, 11, 2, 2, 5, 2, 5, 3, 29, 2, 2, 7, 5, 17, 2, 3, 13, 2, 3, 2, 13, 3, 2, 7, 5, 2, 3, 2, 2, 2

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

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. 2.

LINKS

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

FORMULA

a(n) = A002233(n) for n>1. - Jonathan Sondow, May 18 2017

MAPLE

f:= proc(n) local p, q;

p:= ithprime(n);

q:= 2:

while numtheory:-order(q, p) <> p-1 do q:= nextprime(q) od:

end proc:

map(f, [$1..100]); # Robert Israel, Jan 16 2017

MATHEMATICA

a[1] = 3; a[n_] := (p = Prime[n]; Select[Range[p], PrimeQ[#] && MultiplicativeOrder[#, p] == EulerPhi[p] &, 1]) // First; Table[a[n], {n, 100}] (* Jean-François Alcover, Mar 30 2011 *)

a[1] = 3; a[n_] := SelectFirst[ PrimitiveRootList[ Prime[n]], PrimeQ]; Array[a, 101] (* Jean-François Alcover, Sep 28 2016 *)

CROSSREFS

Cf. A002233 (least prime primitive root).

Sequence in context: A240666 A052901 A127807 * A340300 A245070 A270226

Adjacent sequences: A122025 A122026 A122027 * A122029 A122030 A122031

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane and Klaus Brockhaus, Sep 13 2006

STATUS

approved