I have this formula in a cell

=INDIRECT("'" & B$1 & "'!BT" & (0)*26+4)

and I want to fill the cells below with the same formula with only the number in parenthesis increasing. So the cells below should be

=INDIRECT("'" & B$1 & "'!BT" & (1)*26+4)
=INDIRECT("'" & B$1 & "'!BT" & (2)*26+4)
=INDIRECT("'" & B$1 & "'!BT" & (3)*26+4)

I can create a quick VBA script to do this, but I want to be able to use the drag and fill method to insert the formula. Is there some way to tell excel to change this number and not the other numbers?