Adsense rotation ?

Hey there..

I've just inserted adsense code into my wordpress index.php ... the post loop to be correct....

This would mean that the adsense ads would turn up in the summary of every post on the blog.... <--- be it only if google would allow more then 3 the same adsense ads on 1 page !

So what I actually want to do is : Use 3 adsense ads of the same type by placing them in the loop, and with some counter then switch to something else such as text ads ... or adsense units.....

Is there anyone who knows how I can do this ?

-FOP-