Help with simple for loop

Hey guys, I am new to programming and need help writing a "for" loop in VBA.

I have a variable called "Comment" and I want Comment to start at 3, then increment by 5 every time after that (until it has looped 21 times).

Said another way...

at i = 1, I want Comment = 3
i = 2, Comment = 8
i = 3, Comment = 13
i = 4, Comment = 18
etc.



Thanks!