Find the sum `(sumsum)_(0leiltjlen) ""^(n)C_(i)`.

Explanation

To solve the problem of finding the sum \( \sum_{i=0}^{n} \sum_{j=0}^{n} \binom{n}{i} \), we will break it down step by step.

### Step-by-Step Solution:

1. **Understanding the Double Summation**:
We need to evaluate the double summation \( \sum_{i=0}^{n} \sum_{j=0}^{n} \binom{n}{i} \). Notice that the inner summation does not depend on \( j \). Therefore, we can simplify the expression.

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