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 A240093 #6 Apr 01 2014 05:50:58 %S A240093 2,3,4,5,6,9,10,18,23,25,27,37,41,43,46,50,54,73,74,79,81,82,86,89,97, %T A240093 107,109,125,127,131,137,139,146,149,158,162,178,179,191,194,197,199, %U A240093 214,218,241,243,250,251,254,262,263,274,278,281,283,293,298,317 %N A240093 Numbers with primitive root -13. %H A240093 Vincenzo Librandi, <a href="/A240093/b240093.txt">Table of n, a(n) for n = 1..1000</a> %t A240093 pr = -13; Select[Range[2, 600], MultiplicativeOrder[pr, #] == EulerPhi[#] &] %Y A240093 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). %Y A240093 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). %K A240093 nonn,easy %O A240093 1,1 %A A240093 _Vincenzo Librandi_, Apr 01 2014