Find a Formula for the General Term $a _ { n }$

Short Answer

Find a formula for the general term $a _ { n }$ of the sequence, assuming that the pattern of the first few terms continues.
$$\left\{ - \frac { 1 } { 2 } , \frac { 16 } { 3 } , - \frac { 81 } { 4 } , \frac { 256 } { 5 } , - \frac { 625 } { 6 } , \ldots \right\}$$