Sorry I don’t have the computing resources to give you that answer. However, given 120000 years as a time frame, that’s 4000 generations. Now 2^4000 = (2^10)^400. Since 2^10 is approximately 10^3 (or 1000), 2^4000 is approximately 10^1200. That’s a lot of people, and certainly more than anyone would ever believe that the earth could sustain.
My original post was not meant to suggest that this number of people ever lived, in fact quite the opposite. My calculation was meant to prove that humans are ALL inbred to some degree. This is the number of humans that needed to be alive at a given time in the past to provide enough DISTINCT ancestors so that two randomly-selected individuals would not share any common ancestors. Certainly, my original point is proven; we are all inbred if you look back far enough.