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A243193
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Nonnegative integers represented by the indefinite quadratic form -3x^2+3xy+4y^2.
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3
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0, 1, 4, 6, 7, 9, 16, 19, 24, 25, 28, 36, 42, 43, 49, 54, 58, 61, 63, 64, 73, 76, 81, 82, 87, 96, 100, 106, 112, 114, 118, 121, 123, 133, 139, 142, 144, 150, 157, 159, 163, 168, 169, 171, 172, 175, 177, 178, 196, 199, 213, 214, 216, 225, 226, 229, 232, 244, 252
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OFFSET
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1,3
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COMMENTS
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Discriminant 57.
Note that 4*y^2+3*x*y-3*x^2=n is equivalent to 19*y^2-3*z^2=4*n where z=2*x-y. - Robert Israel, Jun 09 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 09 2014
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MATHEMATICA
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Reap[For[n = 0, n <= 50, 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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