OFFSET
1,2
COMMENTS
Discriminant -35.
LINKS
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
ofTheFormQ[n_] := Reduce[n == 3*x^2 + x*y + 3*y^2, {x, y}, Integers] =!= False; Select[Range[0, 400], ofTheFormQ] (* Jean-François Alcover, Jun 04 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 02 2014
STATUS
approved