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Numbers with primitive root 8.
20

%I #7 Jan 04 2025 00:35:56

%S 3,5,11,25,29,53,59,83,101,107,121,125,131,149,173,179,197,227,269,

%T 293,317,347,389,419,443,461,467,491,509,557,563,587,625,653,659,677,

%U 701,773,797,821,827,841,941,947,1019,1061,1091,1109,1187,1229,1259,1277

%N Numbers with primitive root 8.

%H Vincenzo Librandi, <a href="/A167796/b167796.txt">Table of n, a(n) for n = 1..1000</a>

%t pr=8; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &]

%o (PARI) is(n)=if(n%2==0, return(0)); my(p=eulerphi(n)); znorder(Mod(8, n), p)==p \\ _Charles R Greathouse IV_, Jan 04 2025

%Y Cf. A019338 (primes with primitive root 8)

%K nonn

%O 1,1

%A _T. D. Noe_, Nov 12 2009