OFFSET
1,1
COMMENTS
Primes of the form x^2 + xy + 2y^2, discriminant -7. - N. J. A. Sloane, Jun 01 2014
Primes of the form x^2 - xy + 2y^2 with x and y nonnegative. - T. D. Noe, May 07 2005
Also, primes which are squares (mod 7) (or, (mod 14): see A191017 for a sequence formerly defined as such). - M. F. Hasler, Jan 15 2016
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
Select[Prime[Range[500]], MemberQ[{0, 1, 2, 4}, Mod[#, 7]]&] (* Vincenzo Librandi, Jul 13 2012 *)
PROG
(Magma) [p: p in PrimesUpTo(740)|p mod 7 in [0, 1, 2, 4]]; // Vincenzo Librandi, Jul 13 2012
(PARI) select(p->issquare(Mod(p, 7))&&isprime(p), [1..1000]) \\ M. F. Hasler, Jan 15 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved