A139644 - OEIS

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

%S 109,421,541,709,1009,1129,1201,1381,1429,1549,1621,1789,1801,2221,

%T 2269,2389,2521,2689,3049,3061,3109,3229,3301,3361,3469,3529,3889,

%U 4201,4561,4621,4729,4789,4909,5209,5569,5581,5749,5821,5881,6301

%N Primes of the form x^2 + 105*y^2.

%C Discriminant=-420. See A139643 for more information.

%C The primes are congruent to {1, 109, 121, 169, 289, 361} (mod 420).

%H Vincenzo Librandi and Ray Chandler, <a href="/A139644/b139644.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, 105, 10000] (* see A106856 *)

%o (Magma) [ p: p in PrimesUpTo(7000) | p mod 420 in {1, 109, 121, 169, 289, 361}]; // _Vincenzo Librandi_, Jul 28 2012

%o (Magma) k:=105; [p: p in PrimesUpTo(7000) | NormEquation(k, p) eq true]; // _Bruno Berselli_, Jun 01 2016

%K nonn,easy

%O 1,1

%A _T. D. Noe_, Apr 29 2008