Answer
$n$
Work Step by Step
According to the graph:
$a_1=1=\frac{1}{1}=\frac{1!}{0!}$
$a_2=2=\frac{2\times1}{1}=\frac{2!}{1!}$
$a_3=3=\frac{3\times2\times1}{2\times1}=\frac{3!}{2!}$
...
$a_{10}=10=\frac{10\times9\times8\times7\times6\times5\times4\times3\times2\times1}{9\times8\times7\times6\times5\times4\times3\times2\times1}=\frac{10!}{9!}$
$a_n=\frac{n!}{(n-1)!}$
