If `n` is a positive integer, find the coefficient of `x^(-1)` in the expansion of `(1+x)^n(1+1/x)^ndot`

Explanation

To find the coefficient of \( x^{-1} \) in the expansion of \( (1+x)^n(1+\frac{1}{x})^n \), we can follow these steps:

### Step 1: Rewrite the Expression
We start with the expression:
\[ (1+x)^n \left(1+\frac{1}{x}\right)^n \]
This can be rewritten as:
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