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 A106903 Primes of the form x^2+xy+13y^2, with x and y nonnegative. 2

%I

%S 13,19,43,67,103,127,151,157,223,229,271,307,331,349,373,409,421,433,

%T 457,523,577,613,661,727,733,739,757,769,829,859,883,919,937,967,1021,

%U 1063,1069,1087,1123,1171,1237,1249,1327,1381,1429,1447,1453,1471

%N Primes of the form x^2+xy+13y^2, with x and y nonnegative.

%C Discriminant=-51.

%C Differs from A106904 from a(20) = 523 on, A106904(20) = 463. Since x^2 + xy + y^2 = (x+y)^2 - (x+y)y + y^2, this sequence is a subsequence of A106904. - _M. F. Hasler_, Jan 15 2016

%H Vincenzo Librandi and Ray Chandler, <a href="/A106903/b106903.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, 1, 13, 10000] (* see A106856 *)

%o (PARI) select(p->isprime(p)&&(t=qfbsolve(Qfb(1,1,13),p))&&t[1]>=0,[1..1500]) \\ _M. F. Hasler_, Jan 15 2016

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 09 2005

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Last modified January 26 16:58 EST 2020. Contains 331280 sequences. (Running on oeis4.)