How many ordered triples of positive integers are there such that none of exceeds and each of divides ?
Solution
To find the number of ordered triples of positive integers such that none of exceeds and each of divides , we need to analyze the conditions given.
1. Condition Analysis:
- Each of divides .
- None of exceeds .
2. Rewriting the Problem:
Let . This implies . We need to consider the possible values of under these constraints.
3. Case Analysis:
- Case 1:
- Since are positive integers and , we have .
- This implies , which is always true.
- Therefore, is a valid condition.
- Case 2:
- If , then must be divisible by .
- This implies , , and .
4. Detailed Analysis:
- Subcase 1:
- For each and , .
- Since , we have .
- The number of such pairs is the number of pairs such that .
- Subcase 2:
- We need to find the number of triples such that and .
5. Counting the Triples:
- Case 1:
- For each from to , can range from to .
- The number of such pairs is .
- Case 2:
- This case is more complex and requires further analysis.
6. Summing Up:
- The total number of ordered triples is the sum of the valid triples from both cases.
The final answer is