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A243192
Nonnegative integers represented by the indefinite quadratic form 3x^2+3xy-4y^2.
2
0, 2, 3, 8, 12, 14, 18, 21, 27, 29, 32, 38, 41, 48, 50, 53, 56, 57, 59, 71, 72, 75, 84, 86, 89, 98, 107, 108, 113, 116, 122, 126, 128, 129, 146, 147, 152, 162, 164, 167, 173, 174, 179, 183, 189, 192, 200, 203, 212, 219, 224, 227, 228, 236, 242, 243, 246, 257
OFFSET
1,2
COMMENTS
Discriminant 57.
Note that 3*x^2+3*x*y-4*y^2=n is equivalent to 3*z^2 - 19*y^2=4*n where z=2*x+y. - Robert Israel, Jun 10 2014
LINKS
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
MAPLE
select(m -> nops([isolve(3*z^2-19*y^2=4*m)])>0, [$0..1000]); # Robert Israel, Jun 10 2014
MATHEMATICA
Reap[For[n = 0, n <= 30, n++, If[Reduce[3*x^2 + 3*x*y - 4*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]
CROSSREFS
Cf. A243193. Primes: A141192.
Sequence in context: A128839 A368357 A192113 * A164817 A002958 A290153
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 06 2014
EXTENSIONS
More terms from Colin Barker, Jun 10 2014
STATUS
approved