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 A167806 #14 Nov 25 2014 13:34:19 %S A167806 3,17,29,31,43,61,67,71,83,97,107,109,113,149,151,163,181,191,193,199, %T A167806 227,229,233,257,269,283,289,307,311,313,337,347,359,389,431,433,439, %U A167806 443,461,467,479,509,523,541,563,577,587,593,599,631,683,701,709,719 %N A167806 Numbers with primitive root -10. %C A167806 Note that the term 289 is not a prime and therefore does not appear in A007348. - _Robert G. Wilson v_, Aug 18 2014 %H A167806 Vincenzo Librandi, <a href="/A167806/b167806.txt">Table of n, a(n) for n = 1..1000</a> %t A167806 pr=-10; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &] %o A167806 (PARI) is(n)=if(gcd(n,10)>1, return(0)); my(p=eulerphi(n)); znorder(Mod(-10,n),p)==p \\ _Charles R Greathouse IV_, Nov 25 2014 %Y A167806 Cf. A007348 (primes with primitive root -10). %K A167806 nonn %O A167806 1,1 %A A167806 _T. D. Noe_, Nov 12 2009