Let be an integer. Find the smallest positive integer , such that for any integers there exists integers satisfying the following two conditions:
i) There exists such that and are coprime
ii)
Let be an integer. Find the smallest positive integer , such that for any integers there exists integers satisfying the following two conditions:
i) There exists such that and are coprime
ii)
Let be an integer. We are tasked with finding the smallest positive integer such that for any integers and , there exist integers satisfying the following two conditions:
1. There exists such that and are coprime.
2. .
To solve this, we need to determine the structure of . Let , where are distinct prime factors of and is the number of distinct primes dividing .
We will show that the smallest satisfying the conditions is .
### Construction for :
Consider . Write and let . For each , let divide all of the and 's except for and . Consequently, and must both be divisible by , so none of the 's are coprime to . Thus, is not sufficient.
### Proof for :
To prove that is sufficient, we use the following claim:
Claim: For a prime and a positive integer , is -friendly if and only if is -friendly.
Proof: (Sketch)
1. Base Case: For , the claim is trivially true.
2. Inductive Step: Assume the claim holds for . We need to show it holds for . We consider four cases based on the linear independence and zero properties of the vectors and modulo . By carefully constructing and using the properties of linear combinations and modular arithmetic, we show that the conditions hold for .
By the Chinese Remainder Theorem (CRT), we can reduce the problem to considering each prime power dividing . Since the matrix formed by and has at most entries that do not work, there exists at least one that is coprime to when .
Therefore, the smallest positive integer satisfying the conditions is:
The answer is: .