A106870 Primes of the form x^2+xy+7y^2, with x and y nonnegative.

7, 13, 19, 31, 37, 43, 67, 73, 79, 97, 103, 127, 139, 151, 157, 163, 181, 193, 199, 211, 223, 229, 241, 271, 277, 283, 307, 313, 349, 367, 373, 379, 397, 409, 421, 439, 457, 463, 487, 499, 523, 541, 571, 577, 601, 607, 613, 619, 631, 643, 661, 673, 709, 727

Offset: 1

Author

T. D. Noe, May 09 2005

Keywords

• nonn
• easy

Comments

Discriminant=-27.

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)

Crossrefs

Cf. A243175, A002476.

Programs

Mathematica

QuadPrimes2[1, 1, 7, 10000] (* see A106856 *)