NUMALPHA increment function

I have a field can contain numeric and Alpha value information like following and would like to have it increment

0001, 0002, 0003, 0004, ... 0009,000A, 000B, ....000Z, 0010, 0011, .... 001Z, 0020

I would like to generate the next number from my application for users.

Are there any easy way to have a function to increase just like a numeric number?

Your help and information is great appreciated,

Regards,

Souris,