No, sorry, this is not possible in the general case for any formula plus
having it update automatically. Without using VBA, that is.
However,it can be done for a very small number of specific formula (like concatenating a constant string). It can also be done, but with manual updating, for a certain set of formulas as cleverly shown in VFor's answer.
The closest you can get to a general solution is to rearrange the cells, embed the DOSOMETHING formula in a special wrapper formula, and use helper columns.
For your supplied example worksheet:

Rearrange it like this:

Enter the following formula in D2 and ctrl-enter/copy-paste/fill-down&right/auto-fill into the rest of the table's columns:
=IF(COLUMN()-COLUMN($C2)>$A2,"§",C2&"_checked")
Enter the following formula in B2 and ctrl-enter/copy-paste/fill-down/auto-fill into the rest of the table's column:
=INDEX(C2:INDEX(2:2,1,COLUMNS(2:2)),MATCH("§",C2:INDEX(2:2,1,COLUMNS(2:2)),0)-1)
Note that the number of helper columns required is the maximum allowable value of n plus one. If there aren't enough of them for an entered value, an error ensues:

Explanation:
The generalised wrapper formula for the helper columns is:
=IF(COLUMN()-COLUMN($C2)>$A2,"§",DOSOMETHING(C2))
where DOSOMETHING(C2) is any formula based on C2 only (for example, LEFT(C2,LEN(C2)-1) which progressively removes the last character).
The wrapper formula works by operating on the cell to the left, thus effectively "nesting" the formulas the further to the right in the row it goes.
The IF(COLUMN()-COLUMN($C2)>$A2,"§", part uses the column indexes to count down the number of times the DOSOMETHING formula is nested, and once the number of times specified in column A has been achieved it outputs terminator strings. These strings do not necessarily need to be §. They just need to be something that will never be the result of the evaluation of any number of nested formulas for any allowable Value.
The Result formula looks trickier. However, the C2:INDEX(2:2, 1, COLUMNS(2:2)) parts are simply the sub-range of row 2 to the right of the Result column.
The formula is thus essentially the same as:
=INDEX(2:2,MATCH("§",2:2,0)-1)
which makes it easier to understand.
(Note that this formula actually works if iterative calculations are enabled.)
Looking at this simpler formula, it is clear that the formula returns the n-level nested DOSOMETHING function result.