How many n-bit binary numbers can be formed such that, for every prefix (position) the number of 0's is at least 'x' times than the number of 1's?

Question

For ex- (1) if n = 5 and x=3 Then 3 such binary nos. are possible, which are- 00000, 00001, 00010 All these nos have no of 0's at least 3 times the no of 1's at any prfix(position)

(2) if n=6 and x=2 Then there are 8 possible binary nos satisfying the given condition- 000000, 000001, 000010, 000011, 000100, 000101, 001000, 001001