Fabulous, thank you very much. How did you get from $\displaystyle 2^{n-2}+2^{n-3}+2^{n-4}+...+1+1$ to $\displaystyle 1\left(\frac{2^{n-1}-1}{2-1}\right)+1$, though?
Fabulous, thank you very much. How did you get from $\displaystyle 2^{n-2}+2^{n-3}+2^{n-4}+...+1+1$ to $\displaystyle 1\left(\frac{2^{n-1}-1}{2-1}\right)+1$, though?