Let and be integers with . Prove that the sequence has 2022 consecutive members consisting of composite numbers.
Solution
It is clear if and are not relatively prime, thus we assume that and are relatively prime.
For , let . First we choose such that . Then for any , we have .
In particular, for any , we have . Let and let . Each of has at least one prime divisor, and we choose a prime divisor for each: , , , . Clearly for each .
Now let . Then is divisible by by Fermat's theorem for any . Moreover, . Hence are all composite.
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