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A243192
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Nonnegative integers represented by the indefinite quadratic form 3x^2+3xy-4y^2.
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2
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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
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OFFSET
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1,2
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COMMENTS
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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
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LINKS
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MAPLE
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select(m -> nops([isolve(3*z^2-19*y^2=4*m)])>0, [$0..1000]); # Robert Israel, Jun 10 2014
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MATHEMATICA
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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]]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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