8 Find a formula for the general term an of the sequence, assuming that the pattern of the first few terms continues.
{(1)/(2),(1)/(4),(1)/(6),(1)/(8),(1)/(10),dots}
13. $\left\{\frac{1}{2}, \frac{1}{4}, \frac{1}{6}, \frac{1}{8}, \frac{1}{10}, \ldots\right\}$