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A167794 Numbers with primitive root 6.

%I A167794 #12 Jan 04 2025 00:34:23
%S A167794 11,13,17,41,59,61,79,83,89,103,107,109,113,121,127,131,137,151,157,
%T A167794 169,179,199,223,227,229,233,251,257,271,277,289,347,367,373,397,401,
%U A167794 419,443,449,467,487,491,521,563,569,587,593,613,641,659,661,683,709,733
%N A167794 Numbers with primitive root 6.
%H A167794 Vincenzo Librandi, <a href="/A167794/b167794.txt">Table of n, a(n) for n = 1..1000</a>
%p A167794 A167794 := proc(n)
%p A167794     option remember;
%p A167794     if n =1 then
%p A167794         11;
%p A167794     else
%p A167794         for a from procname(n-1)+1 do
%p A167794             if numtheory[order](6,a) = numtheory[phi](a) then
%p A167794                 return a;
%p A167794             end if;
%p A167794         end do:
%p A167794     end if;
%p A167794 end proc:
%p A167794 seq(A167794(n),n=1..80) ; # _R. J. Mathar_, Sep 15 2021
%t A167794 pr=6; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &]
%o A167794 (PARI) is(n)=if(gcd(n, 6)>1, return(0)); my(p=eulerphi(n)); znorder(Mod(6, n), p)==p \\ _Charles R Greathouse IV_, Jan 04 2025
%Y A167794 Cf. A019336 (primes with primitive root 6). Subsequence of A033948.
%K A167794 nonn
%O A167794 1,1
%A A167794 _T. D. Noe_, Nov 12 2009