1. Any integer can be written in one of the forms: 6k, 6k+1, 6k+2, 6k+3, 6k+4, 6k+5, where \( k \) is an integer.
2. Numbers of the form 6k, 6k+2, and 6k+4 are divisible by 2 and hence not prime (except for 2, which is not greater than 3).
3. Numbers of the form 6k+3 are divisible by 3 and hence not prime (except for 3, which is not greater than 3).
4. Thus, any prime number greater than 3 must be of the form 6k+1 or 6k-1.
**Answer:**
Any prime number greater than 3 must be of the form 6k+1 or 6k-1.