OFFSET
1,3
COMMENTS
Discriminant 257.
32*a(n) has the form z^2 - 257*y^2, where z = 16*x+y. [Bruno Berselli, Jun 20 2014]
LINKS
R. J. Mathar, Table of n, a(n) for n = 1..1676
Peter Luschny, Binary Quadratic Forms
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MATHEMATICA
maxTerm = 400; m0 = 10; dm = 10; Clear[f]; f[m_] := f[m] = Table[8*x^2 + x*y - 8*y^2 , {x, -m, m}, {y, -m, m}] // Flatten // Union // Select[#, 0 <= # <= maxTerm&]&; f[m0]; f[m = m0]; While[f[m] != f[m - dm], m = m + dm]; f[m] (* Jean-François Alcover, Jun 04 2014 *)
PROG
(Sage) # uses[binaryQF]
# The function binaryQF is defined in the link 'Binary Quadratic Forms'.
Q = binaryQF([8, 1, -8])
print([0]+Q.represented_positives(341)) # Peter Luschny, Oct 26 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 02 2014
STATUS
approved