\begin{align}
\label{eqn:L_T}
    \sum\limits_{l=1}^{L_i+1}N^{l}_i = 2\times \frac{2^{L_i-2}\frac{n}{2}}{3^{L_i-1}} + \sum_{l=3}^{L_i+1}\frac{2^{L_i-(l-1)}\frac{n}{2}}{3^{L_i-(l-2)}} = \frac{n}{2}.
\end{align} 
