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

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)