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Primes of the form 21x^2+40y^2.
2

%I #16 Sep 08 2022 08:45:34

%S 61,181,229,349,661,829,1021,1069,1669,1741,1861,2029,2341,2749,3181,

%T 3541,3709,4021,4261,4549,4861,5101,5701,5869,6229,6709,6781,6949,

%U 7069,7549,7621,7741,7789,8221,8389,8461,8581,8629,9421,9901,10069

%N Primes of the form 21x^2+40y^2.

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

%C Also primes of the form 45x^2+30xy+61y^2. See A140633. - _T. D. Noe_, May 19 2008

%H Vincenzo Librandi and Ray Chandler, <a href="/A139993/b139993.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 {61, 181, 229, 349, 661, 829} (mod 840).

%t QuadPrimes2[21, 0, 40, 10000] (* see A106856 *)

%o (Magma) [p: p in PrimesUpTo(12000) | p mod 840 in [61, 181, 229, 349, 661, 829]]; // _Vincenzo Librandi_, Aug 03 2012

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 02 2008