insilico

I want write a script that does the following:

1. Perform a program command
2. Save the file as "a1.jpg"
3. Perform another program command (slightly different)
4. Save the file as "a2.jpg"
5. etc

I need it to loop 360 times then stop. So i end up with 360 files, all slightly different, named a1.jpg, a2.jpg, a3.jpg... a360.jpg

How do I make the digit at the end of the filename increase (+1) in every loop? How do i make it stop after 360 times?

Thanks!