Doubt to asign a valor into CONCAT

Hi everyone,

I have the function =CONCAT(A:A) where i have around 100 variable numbers, i want to delimited the concat into some spaces, for example, into 20 to 31, so i use the function =CONCAT(A20:A31).

I would like to make the limitation of the concat into a changing valor without touching the formula. TO give and example (int doesnt work) =CONCAT(A(B2):A(B3)) where in B2 and B3 you put the first/last enters.

There is any way to do it like that? I would like to not let the users touch the original formula.

Kind regards,

Marti