In detail, needs to match a string with the following pattern:
- Always starts with plain English letters (i.e. A-Z, a-z)
- The length of the above letter is between 1 to 3
- Followed by any numbers of which the first digit is not 0 (i.e. AB01 is not valid but AB1 is)
Thanks.
How about:
which is a literal translation of your remarkably precise question.