A107211 - OEIS

%I #18 Feb 10 2017 16:19:45

%S 2,47,79,97,431,439,521,761,769,929,1193,1223,1297,1303,1399,1481,

%T 1567,1753,1823,1847,2143,2311,2503,2591,2633,2753,2857,3089,3271,

%U 3361,3623,3761,3767,3919,4007,4049,4217,4481,4703,5407,5503,5689

%N Primes of the form 2x^2 + 47y^2.

%C Discriminant = -376. See A107132 for more information.

%H Vincenzo Librandi and Ray Chandler, <a href="/A107211/b107211.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[2, 0, 47, 10000] (* see A106856 *)

%o (PARI) list(lim)=my(v=List(),w,t); for(x=0, sqrtint(lim\2), w=2*x^2; for(y=0, sqrtint((lim-w)\47), if(isprime(t=w+47*y^2), listput(v,t)))); Set(v) \\ _Charles R Greathouse IV_, Feb 10 2017

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 13 2005