OFFSET
1,2
COMMENTS
Discriminant 205.
12*a(n) has the form z^2 - 205*y^2, where z = 6*x+13*y. In fact, this is a particular case of the following identity on the numbers of the form a*x^2+b*x*y+c*y^2: 4*a*(a*x^2+b*x*y+c*y^2) = (2*a*x+b*y)^2-(b^2 -4*a*c)*y^2. [Bruno Berselli, Jun 20 2014]
LINKS
Will Jagy, Sample output from Conway_Positive_All.cc
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
PROG
(C++) // Jagy's program, see link.
// Conway_Positive_All 3 13 -3 500
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 17 2014
STATUS
approved