Answer
It is not a geometric sequence.
Work Step by Step
A sequence is geometric if $\frac{a_2}{a_1}=\frac{a_3}{a_2}=\frac{a_4}{a_3}=...=r$
For the given sequence we have that:
$\frac{a_2}{a_1}=\frac{\frac{1}{2}}{1}=\frac{1}{2}$
$\frac{a_3}{a_2}=\frac{\frac{1}{3}}{\frac{1}{2}}=\frac{1}{3}.\frac{2}{1}=\frac{2}{3}$
It is not a geometric sequence.
