%I #7 Jan 04 2025 00:37:59

%S 3,7,9,11,19,23,27,47,49,59,67,71,79,81,83,103,107,121,131,139,163,

%T 167,179,191,199,211,227,239,243,263,271,311,343,347,359,361,367,379,

%U 383,419,443,463,467,479,487,491,503,523,529,547,563,587,599,607,619,647

%N Numbers with primitive root -4.

%H Vincenzo Librandi, <a href="/A167800/b167800.txt">Table of n, a(n) for n = 1..1000</a>

%t pr=-4; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &]

%o (PARI) is(n)=if(n%2==0, return(0)); my(p=eulerphi(n)); znorder(Mod(-4, n), p)==p \\ _Charles R Greathouse IV_, Jan 04 2025

%Y Cf. A105876 (primes with primitive root -4)

%K nonn

%O 1,1

%A _T. D. Noe_, Nov 12 2009