OFFSET
1,1
COMMENTS
Discriminant=-15.
Subset of A033212. - Robert Israel, Jul 25 2014
LINKS
Vincenzo Librandi and Rick L. Shepherd, Table of n, a(n) for n = 1..10000 (first 2000 terms from Vincenzo Librandi)
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MAPLE
N:= 1000; # to get all terms <= N
Primes:= select(isprime, [seq(2*n+1, n=1..floor((N-1)/2))]):
filter:= proc(p) local S;
S:= remove(hastype, [isolve(x^2+x*y+4*y^2=p)], negint);
nops(S) > 0
end proc:
A:= select(filter, Primes); # Robert Israel, Jul 25 2014
MATHEMATICA
QuadPrimes2[1, 1, 4, 1000000] (* see A106856 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
T. D. Noe, May 09 2005
STATUS
approved