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Primes of the form 20x^2+20xy+47y^2.
2

%I #17 Sep 08 2022 08:45:34

%S 47,167,383,503,647,887,983,1223,1487,1823,1847,2063,2663,2687,2903,

%T 3023,3167,3407,3527,3863,4007,4583,4703,5087,5927,6047,6263,6863,

%U 7103,7607,7703,7727,8447,8543,8783,9623,9743,9887,10223,10247,10463

%N Primes of the form 20x^2+20xy+47y^2.

%C Discriminant=-3360. See A139827 for more information.

%C Also primes of the forms 47x^2+40xy+80y^2 and 47x^2+42xy+63y^2. See A140633. - _T. D. Noe_, May 19 2008

%H Vincenzo Librandi and Ray Chandler, <a href="/A139992/b139992.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)

%F The primes are congruent to {47, 143, 167, 383, 503, 647} (mod 840).

%t QuadPrimes2[20, -20, 47, 10000] (* see A106856 *)

%o (Magma) [p: p in PrimesUpTo(12000) | p mod 840 in [47, 143, 167, 383, 503, 647]]; // _Vincenzo Librandi_, Aug 03 2012

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 02 2008