Problem:
Consider the arithmetic sequence defined by $a_1=-\frac{5}{2}$, and $a_n=a_{n-1}+7 \sqrt{2}$ for $n > 1$. Compute the nth partial sum, $S_n=\sum_{k=1}^n a_k$, where $n=25$.
Answer:
$\frac{25}{2} \left(168 \sqrt{2}-5\right)$
{'source': 'AMPS', 'file': 'amps/mathematica/algebra/arithmetic_series/42825.txt'}