Alphanumeric text increase by 1 every X rows

[MissLauren]

I'm looking for a formula I can copy down one column for the following data pattern:

PNL000372
PNL000372
PNL000372
PNL000373
PNL000373
PNL000373
PNL000374
PNL000374
PNL000374
etc.

Where the number portion of this text increases by 1 every 3rd row. Also, need the option to change to every 4th, 5th row etc.

So far I've figured out how to increase by 1 every 2nd row by using an IF formula, but cannot think of a way to do every 3rd+.

Thank you!

[Ace_XL]

If A1 has your first value, then on A2 use

=IF(COUNTIF($A$1:A1,A1)=3,LEFT(A1,3)&TEXT(RIGHT(A1,6)+1,"000000"),A1) and drag down. Replace the higlighted (in red) number to 4 or 5 or any other number to repeat number of instances as desired

[oeldere]

I have this one for you.

[MissLauren]

This is perfect, thank you so much!!

[oeldere]

I'm always curious which answer you mean.

(To whom you are replying)?