This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A240106 #9 Apr 01 2014 08:49:57 %S A240106 2,4,7,11,13,14,22,23,26,29,37,41,43,46,47,53,58,74,82,83,86,89,94, %T A240106 106,113,121,139,163,166,173,178,191,193,226,239,242,251,257,263,269, %U A240106 278,281,293,311,317,326,337,346,347,359,367,382,386,401,419,433,443 %N A240106 Numbers with primitive root 19. %H A240106 Vincenzo Librandi, <a href="/A240106/b240106.txt">Table of n, a(n) for n = 1..1000</a> %t A240106 pr = 19; Select[Range[2, 500], MultiplicativeOrder[pr, #] == EulerPhi[#] &] %Y A240106 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), A240100 (r=17), A240103 (r=18). %Y A240106 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), A240104 (r=-19). %K A240106 nonn,easy %O A240106 1,1 %A A240106 _Vincenzo Librandi_, Apr 01 2014