A139829 Primes of the form 4x^2+4xy+11y^2.

11, 19, 59, 131, 139, 179, 211, 251, 331, 379, 419, 491, 499, 571, 619, 659, 691, 739, 811, 859, 971, 1019, 1051, 1091, 1171, 1259, 1291, 1451, 1459, 1499, 1531, 1571, 1579, 1619, 1699, 1811, 1931, 1979, 2011, 2099, 2131, 2179, 2251, 2339, 2371

Offset: 1

Author

T. D. Noe, May 02 2008

Keywords

• nonn
• easy

Comments

Discriminant=-160. See A139827 for more information.

Also, primes of form u^2+10v^2 with odd v, while A107145 has even v. One can transform its form as (2x+y)^2+10y^2 (where y can only be odd) and the latter is x^2+10(2y)^2. This sequence has primes {11,19} mod 20 while the second has {1,9} mod 20 and together they are the primes x^2+10y^2 (A033201) which are {1,9,11,20} mod 20. [From Tito Piezas III, Jan 01 2009]

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(3000) | p mod 40 in {11, 19}]; // Vincenzo Librandi, Jul 29 2012

Mathematica

QuadPrimes2[4, -4, 11, 10000] (* see A106856 *)

Formula

The primes are congruent to {11, 19} (mod 40).