* Fundamental Frequency (F): This is the lowest natural frequency of vibration for a specific object (like a string or a pipe). It's the "base" note.

* Overtones: These are frequencies that are whole-number multiples of the fundamental frequency. They create the "harmonics" that add richness to a sound.

To find a frequency that's NOT an overtone of F, we need a frequency that's NOT a whole-number multiple of F.

Example:

Let's say the fundamental frequency F is 100 Hz. Here are some overtones:

* 2F = 200 Hz

* 3F = 300 Hz

* 4F = 400 Hz

A frequency that's NOT an overtone of F would be something like:

* 150 Hz (This is not a whole-number multiple of 100 Hz)

* 255 Hz (This is not a whole-number multiple of 100 Hz)

Without knowing the specific value of F, we can't give a definitive answer. But the key is to find a frequency that cannot be obtained by multiplying F by a whole number.