Answer
$\{s_n\}=n\cdot{(-1)^{n+1}}.$
Work Step by Step
By looking at the pattern: $\{s_n\}=n\cdot{(-1)^{n+1}}.$
Because the sequence begins at $1$ and alternates the sign at each new term and also, the absolute value of the function increases by $1$ at each new term.
