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 A105878 #11 Mar 31 2024 15:03:19 %S A105878 13,17,19,23,41,47,61,67,71,89,109,113,137,157,167,211,229,233,257, %T A105878 263,277,283,331,359,373,383,397,401,449,479,503,521,523,547,569,593, %U A105878 599,613,619,641,647,661,691,709,719,733,739,743,757,761,787,809,811,829,839,853 %N A105878 Primes for which -6 is a primitive root. %H A105878 Vincenzo Librandi, <a href="/A105878/b105878.txt">Table of n, a(n) for n = 1..1000</a> %H A105878 <a href="/index/Pri#primes_root">Index entries for primes by primitive root</a> %t A105878 pr=-6; Select[Prime[Range[200]], MultiplicativeOrder[pr, # ] == #-1 &] %o A105878 (PARI) is(n)=isprime(n) && n>7 && znorder(Mod(-6,n))==n-1 \\ _Charles R Greathouse IV_, Feb 23 2017 %K A105878 nonn %O A105878 1,1 %A A105878 _N. J. A. Sloane_, Apr 24 2005