(Pardon if this seems a bit beginner, this is my first post in math - trying to improve my knowledge while tackling Project Euler problems)
I'm aware of Sigma notation, but is there a function/name for e.g.
$$ 4 + 3 + 2 + 1 \longrightarrow 10 ,$$
similar to $$4! = 4 \cdot 3 \cdot 2 \cdot 1 ,$$ which uses multiplication?
Edit: I found what I was looking for, but is there a name for this type of summation?