Find all integers , not necessarily positive, for which there exist positive integers satisfying .
Solution
By Fermat's Last Theorem, we know . Suppose . Then , but since , this is also impossible by Fermat's Last Theorem. As a result, . Furthermore, , as , which is false. We now just need to find constructions for . When suffices, and when works nicely. When works, and when is one example. Therefore, the working values are .
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