Because I am studying in depth the array formulas, I would like to
know if it is possible to build a formula such that, given a set of
numbers in a vertical range (1 column wide), it returns an array with
the cumulative sum.

For example, if A1:A5 contains:

3
8
5
1
6

Then, the formula should return

3
11
16
17
23

Of course, I know that the goal can be achieved by mean of a simple
formula:

=SUM($A$1:A1) copied down

However, I keep an interest (let's call it theoretical) in knowing if
the exercise is possible?

Can anybody help?