Find rules 3, 5, 9, 18, () 129 Find the law

Find rules 3, 5, 9, 18, () 129 Find the law

Is the question wrong? If it's 3 59 17 129, it's easy to find a rule
3=2^1+1
5=2^2+1
9=2^3+1
17=2^4+1
33=2^5+1
65=2^6+1
129=2^7+1