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 A323576 #38 Feb 16 2025 08:33:57 %S A323576 29,197,211,379,421,491,547,659,701,757,827,883,1373,1499,1667,1877, %T A323576 2213,2269,2339,2437,2549,2843,3011,3067,3347,3557,3571,3613,3851, %U A323576 3907,4019,4229,4243,4397,4621,4691,4789,4957,5573,5741,5923,6203,6469,6637,6763,6917 %N A323576 Primes p such that 2 is a primitive root modulo p while 128 is not. %C A323576 Primes p such that 2 is a primitive root modulo p (i.e., p is in A001122) and that p == 1 (mod 7). %C A323576 According to Artin's conjecture, the number of terms <= N is roughly ((6/41)*C)*PrimePi(N), where C is the Artin's constant = A005596, PrimePi = A000720. Compare: the number of terms of A001122 that are no greater than N is roughly C*PrimePi(N). %H A323576 Amiram Eldar, <a href="/A323576/b323576.txt">Table of n, a(n) for n = 1..10000</a> %H A323576 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ArtinsConstant.html">Artin's constant</a>. %H A323576 Wikipedia, <a href="https://en.wikipedia.org/wiki/Artin%27s_conjecture_on_primitive_roots">Artin's conjecture on primitive roots</a>. %o A323576 (PARI) forprime(p=3, 7000, if(znorder(Mod(2, p))==(p-1) && p%7==1, print1(p, ", "))) %Y A323576 Cf. A001122, A005596, A000720. %Y A323576 Primes p such that 2 is a primitive root modulo p and that p == 1 (mod q): A307627 (q=3), A307628 (q=5), this sequence (q=7), A323577 (q=11), A323590 (q=13). %K A323576 nonn %O A323576 1,1 %A A323576 _Jianing Song_, Aug 30 2019