n = number of players
r = rank (k)
bc = cost of buy-in (b)
10 * (sqrt(n)/sqrt(r)) * (1 + (log(bc) / log(25)))
The Tournament Director currently has two functions for log: log(), which is log base e, and log10(), which is log base 10. To accomplish log() using a different base, you must use log() divided by log(base). The next version will allow for a second argument to the log() function to specify a base.