A100141 Numbers n such that the number of prime primitive roots of n is a prime primitive root of n

5, 9, 11, 19, 23, 34, 37, 38, 46, 67, 94, 121, 167, 178, 194, 269, 274, 281, 358, 382, 457, 521, 601, 625, 626, 698, 709, 719, 818, 839, 958, 1006, 1094, 1217, 1303, 1402, 1439, 1453, 1493, 1502, 1579, 1601, 1663, 1706, 1838, 1871, 1901, 1913, 1922, 2011, 2066

Offset

1,1

Comments

A100142(n) gives the number of prime primitive roots of these numbers.

Links

Amiram Eldar, Table of n, a(n) for n = 1..1000

Example

19 has prime primitive roots 2, 3, 13. Count is 3, which is a prime primitive root of 19.

Mathematica

q[n_] := Module[{p = Select[PrimitiveRootList[n], PrimeQ], m}, m = Length[p]; MemberQ[p, m] && PrimeQ[m]]; Select[Range[2000], q] (* Amiram Eldar, Sep 25 2021 *)

Crossrefs

Cf. A100142.

Sequence in context: A101284 A362156 A102182 * A314604 A309137 A190894

Adjacent sequences: A100138 A100139 A100140 * A100142 A100143 A100144

Keyword

easy,nonn

Author

Sven Simon, Nov 07 2004

Extensions

a(2) inserted by Amiram Eldar, Sep 25 2021

Status

approved