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 A167802 #7 Feb 23 2017 02:25:59 %S A167802 13,17,19,23,41,47,61,67,71,89,109,113,137,157,167,169,211,229,233, %T A167802 257,263,277,283,289,331,359,361,373,383,397,401,449,479,503,521,523, %U A167802 529,547,569,593,599,613,619,641,647,661,691,709,719,733,739,743,757,761 %N A167802 Numbers with primitive root -6. %H A167802 Vincenzo Librandi, <a href="/A167802/b167802.txt">Table of n, a(n) for n = 1..1000</a> %t A167802 pr=-6; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &] %o A167802 (PARI) is(n)=gcd(n,6)==1 && znorder(Mod(-6,n))==eulerphi(n) && n>1 \\ _Charles R Greathouse IV_, Feb 23 2017 %Y A167802 Cf. A105878 (primes with primitive root -6) %K A167802 nonn %O A167802 1,1 %A A167802 _T. D. Noe_, Nov 12 2009