Which recursive definition represents the sequence {2, 3, 5, 9, 17 ... }?

Let's analyze the sequence: {2,3,5,9,17 ... }.

3 = 2+1

5 = 3+2

9=5+4

17=9+8

So, every element of the sequence is obtained as sum from the previous element + (previous element - 1)

y[n]=y[n-1] + (y[n-1]-1)