Find a formula for the general term $a_n$ of the sequence, assuming that the pattern of the first few terms continues.

${4, -2, 4, -2, dots}$

$a_n = ?$

What is the formula for the general term $a_n$ of the sequence?

I know that it starts in the numerator with $(-1)^{n-1}$ in order to alternate between positive and negative, but I can’t seem to figure out the rest.

The homework problem I am working on requires it to be a non-piecewise function.