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A107196 Primes of the form 4x^2 + 21y^2. 1

%I

%S 37,193,277,421,541,673,1009,1033,1093,1129,1201,1213,1429,1549,1621,

%T 1789,1801,2053,2137,2377,2473,2521,2557,2689,2797,2857,3217,3229,

%U 3301,3529,3613,3637,3697,3733,3889,4201,4621,4657,4729,4789,4813

%N Primes of the form 4x^2 + 21y^2.

%C Discriminant = -336. See A107132 for more information.

%H Vincenzo Librandi and Ray Chandler, <a href="/A107196/b107196.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[4, 0, 21, 10000] (* see A106856 *)

%o (PARI) list(lim)=my(v=List(),w,t); for(x=1, sqrtint(lim\4), w=4*x^2; for(y=1, sqrtint((lim-w)\21), if(isprime(t=w+21*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

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Last modified November 11 22:31 EST 2019. Contains 329046 sequences. (Running on oeis4.)