nptel lecture on stacks

Question

While calculating the cost of growable array-based stack.... the cost of n pushes came out as a series - 2 + 4 + 8 + 16 +......+2^(logn + 1) and it equals to 4n - 1. I didn't understand how the series sum equals to 4n?

Answer 1

it should be 4n-2

Comments

Thank you so much