Problem:
Are there any positive integers and satisfying the equation
Junior Balkan Mathematical Olympiad
Solution
Solution:
We will prove that the answer is no. Note that
If is odd then is even, therefore . However,
which leads to a contradiction. If is a multiple of then so is and hence is a multiple of , which is absurd. For even and not multiple of , since
this gcd must be . Therefore for an odd , so
For we have , while for we have . Thus has a prime divisor of type . As it divides , it has to divide and , which is absurd.
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