What are the first four terms of the sequence a1=−9 and an+1=an+n. I really need help with this im struggling

The formatting was a bit confusing, so please do let me know if this isn't the correct equation for the sequence.

The first term is given, which is

Now, use the equation for the next terms:

Thus, the first 4 terms are -9, -8, -6, and -3. Let me know if you need any clarifications, thanks!