A240102 - OEIS

%I #7 Nov 26 2014 13:40:42

%S 5,7,23,29,31,37,47,53,61,71,101,103,109,127,149,151,157,167,173,181,

%T 191,197,223,239,263,269,271,277,293,317,349,359,367,383,389,397,421,

%U 461,479,503,509,529,541,557,607,613,647,653,661,677,701,719,733

%N Numbers with primitive root -18.

%H Vincenzo Librandi, <a href="/A240102/b240102.txt">Table of n, a(n) for n = 1..1000</a>

%t pr = -18; Select[Range[2, 800], MultiplicativeOrder[pr, #] == EulerPhi[#] &]

%o (PARI) is(n)=if(gcd(n,6)>1, return(0)); my(p=eulerphi(n)); znorder(Mod(-18,n),p)==p \\ _Charles R Greathouse IV_, Nov 26 2014

%Y Cf. numbers with positive primitive root r: A167791 (r=2), A167792 (r=3), A167793 (r=5), A167794 (r=6), A167795 (r=7), A167796 (r=8), A167797 (r=10), A240028 (r=11), A240030 (r=12), A240032 (r=13), A240094 (r=14), A240096 (r=15), A240101 (r=17), A240103 (r=18).

%Y Cf. numbers with negative primitive root r: A167798 (r=-2), A167799 (r=-3), A167800 (r=-4), A167801 (r=-5), A167802 (r=-6), A167803 (r=-7), A167804 (r=-8), A167805 (r=-9), A167806 (r=-10), A240029 (r=-11), A240031 (r=-12), A240093 (r=-13), A240095 (r=-14), A240097 (r=-15), A240100 (r=-17).

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Apr 01 2014