OFFSET
1,2
COMMENTS
Discriminant 28.
Nonnegative numbers of the form 7x^2 - y^2. - Jon E. Schoenfield, Jun 03 2022
For the subsequence of the numbers with proper representations (gcd(x, y) = 1) see A359476. ~ Wolfdieter Lang, Jan 17 2023
LINKS
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
Reap[For[n = 0, n <= 300, n++, If[Reduce[-x^2 + 4*x*y + 3*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 31 2014
STATUS
approved