Given a sequence:
$$1, \frac12, \frac13, \frac14, \frac15,...$$
Its explicit formula can be given as:
$a(n) = \frac1n$ where $n \ge 1$.
I actually want to know is it a geometric sequence or an arithmetic one?
I tried finding common ratio and the common difference in this sequence to see if it's either one of them but was not successful.
My common ratio ($r$) and common difference ($d$) were some horrible values.