Abstract
There are 18 (and possibly 19) integers that are not of the form $ xy + yz + xz $ with positive integers $x, y, z$. The same 18 integers appear as exceptional discriminants for which no indecomposable positive definite binary quadratic form exists. We show that the two problems are equivalent.
Citation
Meinhard Peters. "The Diophantine Equation $ xy + yz + xz = n $ and Indecomposable Binary Quadratic Forms." Experiment. Math. 13 (3) 273 - 274, 2004.
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