\[a_{n} = 8n\]
\[8n \leq 200\]
\[n \leq \frac{200}{8} \leq 25\]
\[n = 25.\]
\[a_{1} = 8;\ \ a_{25} = 200:\]
\[S_{25} = \frac{8 + 200}{2} \cdot 25 =\]
\[= 104 \cdot 25 = 2600.\]
\[Ответ:2600.\]