%I #11 Apr 01 2014 08:50:01
%S 2,3,6,13,26,29,31,37,41,53,58,59,62,67,71,74,79,82,89,103,106,107,
%T 113,118,134,142,158,167,173,178,179,193,206,214,223,226,227,257,269,
%U 281,293,317,331,334,337,346,358,379,383,386,401,431,433,439,446,449
%N Numbers with primitive root -19.
%H Vincenzo Librandi, <a href="/A240104/b240104.txt">Table of n, a(n) for n = 1..1000</a>
%t pr = -19; Select[Range[2, 500], MultiplicativeOrder[pr, #] == EulerPhi[#] &]
%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), A240106 (r=19).
%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), A240102 (r=-18).
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Apr 01 2014