A167798 Numbers with primitive root -2.

5, 7, 13, 23, 25, 29, 37, 47, 49, 53, 61, 71, 79, 101, 103, 125, 149, 167, 169, 173, 181, 191, 197, 199, 239, 263, 269, 271, 293, 311, 317, 343, 349, 359, 367, 373, 383, 389, 421, 461, 463, 479, 487, 503, 509, 529, 541, 557, 599, 607, 613, 625, 647, 653, 661

Offset: 1

Author

T. D. Noe, Nov 12 2009

Keywords

• nonn

Comments

Numbers k such that the largest primitive root of k is k-2. - Davide Rotondo, Dec 20 2024

Links

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

Crossrefs

Cf. A105874 (primes with primitive root -2).

Programs

Mathematica

pr=-2; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &]

PARI

is(n)=if(n%2==0, return(0)); my(p=eulerphi(n)); znorder(Mod(-2, n), p)==p \\ Charles R Greathouse IV, Jan 04 2025