I'm doing a sequences problem where I have to write the first five terms of a sequence. It looks normal, but there is an exclamation mark on the denominator:
$a_n = \frac{1}{(n + 1)!}$
&
$a_n = \frac{(-1)^{n}n}{n! + 1}$
What does the exclamation mark mean, and how do I go about this differently with the exclamation mark?