\[4;4^{2};\ldots\]
\[b_{1} = 4;\ \ b_{2} = 4^{2};\ \ q = \frac{4^{2}}{4} = 4.\]
\[S_{6} = \frac{4 \cdot \left( 4^{6} - 1 \right)}{4 - 1} =\]
\[= \frac{4 \cdot (4096 - 1)}{3} = \frac{4 \cdot 4095}{3} =\]
\[= 4 \cdot 1365 = 5460.\]