Gonna have to better than that to kill the thread. There's just not that many people here, which is why every contribution is helpful.
I've gone over that crumb a few times, but I don't know what to do with it because we still don't have a way of getting the NA we want. We know the answer is 25, and that the (N-1)A is 20, but we don't have a way to reach that answer. Maybe you could do some kind of Fourier transform but I don't know.
If I had to guess, the medium sized moments would be an exponential growth formula which intersects with the factor cell.
The only note I have about F, is that any (E,D) with any values for (N,X,A,B) all have the same F. The inverse is true for any (F,D) with any (N,X,A,B) - they all have the same E.