OFFSET
1,3
COMMENTS
Discriminant 60.
Also numbers representable as x^2 + 8*x*y + y^2 with 0 <= x <= y. - Gheorghe Coserea, Jul 29 2018
Also numbers of the form x^2 - 15*y^2. - Jianing Song, Jul 31 2018
LINKS
Gheorghe Coserea, Table of n, a(n) for n = 1..100001
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
Reap[For[n = 0, n <= 200, n++, If[Reduce[ 1*x^2 + 6*x*y - 6*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 05 2014
EXTENSIONS
More terms from Colin Barker, Apr 07 2015
STATUS
approved