F={x aparține N/ x=2n-1, 4< n <8

I don't know the precise question you are asking, but based on the provided information, it seems you are defining a set F. F is the set of all odd numbers (x) such that x is greater than 4 and less than 8, represented by the formula x = 2n - 1, where n belongs to the set of natural numbers (N) and satisfies the condition 4 < n < 8.