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 A381590 #21 May 29 2025 00:43:09 %S A381590 3,7,19,23,31,43,47,59,67,71,83,107,131,151,163,167,179,191,199,223, %T A381590 227,263,283,307,311,347,359,367,379,383,419,431,439,443,467,479,487, %U A381590 491,499,503,523,563,571,587,599,619,631,647,659,683,719,727,743,787,811 %N A381590 Primes with primitive root -100. %C A381590 Union of long period primes (A006883) of the form 4k-1 and half period primes (A097443) of the form 4k-1. %C A381590 Complement of A007349 in the union of A007348 and A001913. - _Davide Rotondo_, May 23 2025 %t A381590 Select[Prime[Range[150]], MultiplicativeOrder[-100, #] == # - 1 &] (* _Amiram Eldar_, Mar 02 2025 *) %o A381590 (PARI) is(n)=gcd(n,10)==1 && znorder(Mod(-100, n))==n-1 \\ _Charles R Greathouse IV_, Mar 01 2025 %o A381590 (PARI) list(lim)=my(v=List([3])); forprime(p=7,lim, if(znorder(Mod(-100, p))==p-1, listput(v,p))); Vec(v) \\ _Charles R Greathouse IV_, Mar 01 2025 %Y A381590 Cf. A006883, A097443, A007349, A007348, A001913. %K A381590 nonn,easy %O A381590 1,1 %A A381590 _Davide Rotondo_, Feb 28 2025