$\mathop \sum \limits_{0 \le i < j \le n} i\left( \begin{array}{l}
n\\
j
\end{array} \right)$ is equal to
$\mathop \sum \limits_{0 \le i < j \le n} i\left( \begin{array}{l}
n\\
j
\end{array} \right)$ is equal to
- A
$n^22^{n-1}$
- B
$(n^2 -1)2^{n-1}$
- C
$(n-1)^22^n$
- D
$n(n-1)2^{n-3}$
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