The number pattern?????

Rewrite the [num] in terms of halves: 0/2, -1/2, -4/2, -9/2, -16/2. The numerators are all negative and they are also PERFECT SQUARES of the term number. Thus, the next [num] is -25/2 (or -12.5). Thus, the Nth term will give the -(N^2)/2