Data generate using Regex

Hello,

I want to generate data using regex say for: [a-zA-Z]{1}\d{8}
How do I use this? because when I enter this reg ex in field I am not displayed with proper output.
I am displayed with something like
[a-zA-Z]{1}23456789

Need urgent help

Take a look at this schema I just put together for you: https://mockaroo.com/2fe44830