Why Is My Proof Of Asymptomatic Time Complexity Of A Dynamic Array Using The Accounting Method Getting A Wrong Answer?
First of all notice that your first aggregate analysis should read $\sum_{i=1}^{\log n} 2^i = 2^{\log n + 1} - 2 &lt; 2n$. (What you have written makes no sense since $\sum_{i=1}^\infty \frac{1}{2^i} \le 1$, which would mean that the aggregate complexity is upper bounded by a constant regardless of the number of operations).

Then in your last analysis you can't just place one extra credit on each element because it would only pay for the first time that such element is copied (i.e., only for the next insertion).