\begin{equation}
\sum_{\frac{n}{2}>5} n^2
\end{equation}
\begin{equation}
\sum_{\genfrac{}{}{}{}{n}{2}>5} n^2
\end{equation}
\begin{equation}
\genfrac{(}{)}{}{}{n}{2}>5
\end{equation}
\begin{equation}
\left(\frac{n}{2}\right)>5
\end{equation}
\begin{equation}
\sum_{\left(\frac{n}{2}\right)>5} n^2
\end{equation}
\begin{equation}
\sum_{\genfrac{(}{)}{}{}{n}{2}>5} n^2
\end{equation}