What comes after a sequel, and then after that, etc?

In many cases, the sequel continues elements of the original story, often with the same characters and settings. A sequel can lead to a series, in which key elements appear in a number of stories. Although the difference between more than one sequel and a series is somewhat arbitrary, it is clear that some media franchises have enough sequels to become a series, whether originally planned as such or not.

https://en.wikipedia.org/wiki/Sequel