Hey uptowngirl!

Look at the part 2+2. It is 4, right ? or 2^2.
Hence, we can factor 2^2 from two first figures.
i mean
[2^2+2^2]+2^3...=2^2(1+1)+2^3.....=2*2^2+2^3...=2^3+2^3+2^4...

Notice since that moment factoring 2^n will result in increasing of the next number's power by 1 at a time.
4 5 6 7 8 9 ===> 2^9 is your answer.