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 A377177 #24 Nov 11 2024 09:01:27 %S A377177 11,17,29,31,37,41,43,47,73,89,103,107,109,149,167,179,197,257,277, %T A377177 311,313,317,347,353,367,373,383,389,409,433,479,491,499,503,521,541, %U A377177 557,571,577,593,601,607,647,653,659,683,701,719,727,761,769,821,839,857,883,887,907,929,937,947,983 %N A377177 Primes p such that -7/2 is a primitive root modulo p. %C A377177 If p is a term in this sequence, then -7/2 is not a square modulo p (i.e., p is in A191061). %C A377177 Conjecture: this sequence has relative density equal to Artin's constant (A005596) with respect to the set of primes. %H A377177 Robert Israel, <a href="/A377177/b377177.txt">Table of n, a(n) for n = 1..10000</a> %H A377177 Wikipedia, <a href="https://en.wikipedia.org/wiki/Artin%27s_conjecture_on_primitive_roots">Artin's conjecture on primitive roots</a>. %H A377177 <a href="/index/Pri#primes_root">Index entries for primes by primitive root</a> %p A377177 select(p -> isprime(p) and numtheory:-order(-7/2 mod p, p) = p-1, [seq(i,i=3..1000,2)]); # _Robert Israel_, Nov 10 2024 %t A377177 Cases[Prime[Range[2,170]],_?(MemberQ[PrimitiveRootList[#],ResourceFunction["FractionMod"][-7/2,#]]&)] (* _Shenghui Yang_, Oct 23 2024 *) %o A377177 (PARI) forprime(p=8,10^3,if(znorder(Mod(-7/2,p))==p-1,print1(p,", "))); \\ _Joerg Arndt_, Oct 19 2024 %Y A377177 Primes p such that +a/2 is a primitive root modulo p: A320384 (a=3), A377174 (a=5), A377176 (a=7), A377178 (a=9). %Y A377177 Primes p such that -a/2 is a primitive root modulo p: A377172 (a=3), A377175 (a=5), this sequence (a=7), A377179 (a=9). %Y A377177 Cf. A191061, A005596. %K A377177 nonn,easy %O A377177 1,1 %A A377177 _Jianing Song_, Oct 18 2024