If m and n are positive integers, can the number m4+2mn+n2−2021 be the product of three or more consecutive integers?
Solution
Answer: No. Suppose that N=m4+2mn+n2−2021 is the product of three or more consecutive integers. Then N and m4−m2=m[(m−1)m(m+1)] are divisible by 3. Thus (m+n)2≡N−(m4−m2)+2021≡2(mod3), which is a contradiction, since 2 is not a quadratic residue modulo 3.
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