Note that $a_n\>0$ for all $n\ge 0$, and write the general term in the sequence as

$a_n\&equals;\left(\frac{5\cdot 5\cdot 5\cdot 5\cdot 5}{1\cdot 2\cdot 3\cdot 4\cdot 5}\right)\cdot \left(\frac{5}{6}\cdot \frac{5}{7}\cdot \frac{5}{8}\cdot \cdots \cdot \frac{5}{n}\right)<\frac{5^4}{4\&excl;}\cdot \left(\frac{5}{5}\cdot \frac{5}{5}\cdot \cdots \cdot \frac{5}{5}\cdot \frac{5}{n}\right)\&equals;\frac{5^5}{4\&excl;}\cdot \frac{1}{n}$ 

from which it follows by a discrete form of the Squeeze theorem that $\underset{n\to \infty }{lim}{a}_n\&equals;0$.

Table 8.1.6(a) contains the  task template that, given the general term of a sequence, calculates and graphs its first few members.

Place the cursor somewhere in the cell containing the phrase "General term"and press the Tab key often enough for the cursor to move to, and select the default general term. With this expression auto-selected, simply overwrite with the desired general term, most easily obtained by a copy/paste operation. Then, adjust any of the inputs as needed, and simply press the Enter key to execute each command in the template.