AM 1.0: What was that very first lesson??

I first used AM a few years ago in the 1.0 or maybe even during the Beta days. I remember that the very first thing I made with it was a suggested project which made an "infinite loop" of sorts. It was a simple sine wave that swept thru a very low frequency to a very high one at the same time as it swept from very high to very low. This created an effect of hearing a tone infinitely rise and fall at the same time, never ending.

"Gaussian Loop"??? "Infinite Loop"???? I really need to use this sound now and can't figure out how to make it or what it was called.

Anybody remember this? Or have any idea what I'm talking about?

Thanks for any help you can offer!