A139850 Primes of the form 11x^2 + 8xy + 11y^2.

11, 71, 179, 191, 239, 359, 431, 491, 599, 659, 911, 1019, 1031, 1439, 1451, 1499, 1619, 1871, 2039, 2111, 2339, 2459, 2531, 2591, 2699, 2711, 2879, 3011, 3119, 3299, 3371, 3539, 3719, 3851, 4019, 4139, 4211, 4271, 4391, 4691, 4799, 5051

Offset: 1

Author

T. D. Noe, May 02 2008

Keywords

• nonn
• easy

Comments

Discriminant = -420. See A139827 for more information.

Also primes of the forms 11x^2 + 6xy + 39y^2 and 11x^2 + 10xy + 50y^2. See A140633. - T. D. Noe, May 19 2008

Links

• Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]
• N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

Programs

Magma

[ p: p in PrimesUpTo(6000) | p mod 420 in {11, 71, 179, 191, 239, 359}]; // Vincenzo Librandi, Jul 29 2012

Mathematica

Union[QuadPrimes2[11, 8, 11, 10000], QuadPrimes2[11, -8, 11, 10000]] (* see A106856 *)

PARI

list(lim)=my(v=List(), s=[11, 71, 179, 191, 239, 359]); forprime(p=11, lim, if(setsearch(s, p%420), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 10 2017

Formula

The primes are congruent to {11, 71, 179, 191, 239, 359} (mod 420).