Find the sixth term of the geometric progression $2, 6, 18, \ldots$

The common ratio is $r = 3$ and the $n$th term is $ar^{n-1}$, so the sixth term is $2 \times 3^5 = 2 \times 243 = 486$. Using $r^n$ instead of $r^{n-1}$ gives 1458, and $r^{n-2}$ gives 162.