No.

Americium, in gram quantities, emits potentially harmful amounts of gamma rays. This guy was talking about collecting a kilogram.

One gram of Americium can be used to make more than 5000 smoke detectors. Thus, you’d need 5000*1000 = 5,000,000 smoke detectors to get to what he considers ”critical mass".

Only several kilograms of Americium are produced each year.

I’ve only read of three materials which can, for various reasons, be used in a fission bomb. U-233, U-235, and Pu-239. These are the “easy” ones. Assuming that you can even get Americium to participate in a fission chain reaction (and I’m very skeptical about that), you’d probably need at least as much Am as you would U or Pu – and the critical mass for those elements is >10 kilograms. So, you’d need at least ten times the amount he was talking about. Now, we’re up to 50,000,000 smoke detectors.

The formula he gives, and its ”meaning” are completely bogus, as far as I can tell. And unless you explain what the variables are, the formula is useless anyway.