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A139660 Primes of the form x^2 + 385*y^2. 2

%I #21 Sep 08 2022 08:45:33

%S 389,401,421,449,641,709,1061,1409,1549,1621,1709,1901,2069,2269,2381,

%T 2689,2909,3061,3089,3221,3301,3389,3469,3529,4229,4349,4481,4621,

%U 4789,4909,5009,5021,5261,5569,5581,5861,6029,6301,6329,6449,6469

%N Primes of the form x^2 + 385*y^2.

%C Discriminant=-1540. See A139643 for more information.

%C The primes are congruent to {1, 9, 81, 141, 169, 221, 289, 309, 361, 389, 401, 421, 449, 529, 641, 669, 709, 729, 841, 949, 961, 1061, 1101, 1149, 1241, 1269, 1369, 1401, 1409, 1521} (mod 1540).

%H Vincenzo Librandi and Ray Chandler, <a href="/A139660/b139660.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, 0, 385, 10000] (* see A106856 *)

%o (Magma) */ k:=385; [p: p in PrimesUpTo(6500) | NormEquation(k, p) eq true]; // _Bruno Berselli_, Jun 01 2016

%K nonn,easy

%O 1,1

%A _T. D. Noe_, Apr 29 2008

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Last modified July 9 00:53 EDT 2024. Contains 374171 sequences. (Running on oeis4.)