Here is what I have and where I am stuck...

Repeat substitution...

Now what? I know the base case is T(2) = 2...

I can see the repeating pattern, but I'm not sure what to do next.

Since k = logn (in base 2), and our base case is T(2) = 2

would the general form be something like...

2^(k-1) * T(n/2^[k-1]) + 2^[k-1] + 2^[k-2] + ... + 2? (i would use math tags so this looks easier but for some reason the exponents aren't coming out right with the ^ sign)