A106989 - OEIS

%I #24 Jan 15 2016 09:04:14

%S 23,29,43,53,79,107,113,127,179,191,211,233,263,277,337,347,373,389,

%T 443,491,547,569,571,599,641,653,659,673,701,751,757,809,823,883,907,

%U 911,919,953,991,1031,1093,1117,1171,1187,1213,1283,1297,1303,1327

%N Primes of the form x^2-xy+23y^2, with x and y nonnegative.

%C Discriminant=-91.

%C Also, primes that are squares (mod 91), or equivalently, with Legendre symbols (p|7) = (p|13) = 1. Included as subsequence in A191054 which are primes with Jacobi symbol (p|7*13) = 1, including also primes with (p|7) = (p|13) = -1. - _David Broadhurst_ and _M. F. Hasler_, Jan 15 2016

%H Vincenzo Librandi and Ray Chandler, <a href="/A106989/b106989.txt">Table of n, a(n) for n = 1..10000</a> [First 1000 terms from Vincenzo Librandi]

%H N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)

%t QuadPrimes2[1, -1, 23, 10000] (* see A106856 *)

%o (PARI) is(p)=issquare(Mod(p,91))&&isprime(p) \\ _M. F. Hasler_, Jan 15 2016

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 09 2005