Calculates the lowest exponent of 2 so that a power of 2 with this exponent is at least n / load_factor.
number of expected elements in the set
desired maximum load factor
exponent of 2.
In: load_factor must be greater than 0.
See Implementation
Calculates the lowest exponent of 2 so that a power of 2 with this exponent is at least n / load_factor.