cp's OEIS Frontend

A213050 Primes of the form 4*k+1 with primitive root +2.

%I A213050 #20 Oct 11 2021 04:38:10
%S A213050 5,13,29,37,53,61,101,149,173,181,197,269,293,317,349,373,389,421,461,
%T A213050 509,541,557,613,653,661,677,701,709,757,773,797,821,829,853,877,941,
%U A213050 1061,1109,1117,1213,1229,1237,1277,1301,1373,1381,1453,1493,1549,1621
%N A213050 Primes of the form 4*k+1 with primitive root +2.
%C A213050 Primes p such that both +2 and -2 are primitive roots mod p.
%C A213050 A001122 is the union of A213050 and A213051.
%H A213050 Amiram Eldar, <a href="/A213050/b213050.txt">Table of n, a(n) for n = 1..10000</a>
%t A213050 Select[Prime[Range[300]], Mod[#, 4] == 1 && PrimitiveRoot[#, 2] == 2&] (* _Jean-François Alcover_, Jul 22 2018 *)
%o A213050 (PARI)
%o A213050 { forprime (p=3, 10^4,
%o A213050     rp = znorder(Mod(+2,p));
%o A213050     rm = znorder(Mod(-2,p));
%o A213050     if ( (rp==p-1) && (rm==p-1), print1(p,", ") );
%o A213050 );}
%Y A213050 Cf. A213051 (primes 4*k+3 with primitive root +2).
%Y A213050 Cf. A001122 (primitive root +2), A007885 (primitive root +2 or -2).
%K A213050 nonn
%O A213050 1,1
%A A213050 _Joerg Arndt_, Jun 03 2012