I'm with Roy but perhaps even stronger. You NEVER touch an autonumber field as anything other than a foreign key in another table. If you have to tweak an autonumber it categorically and absolutely should not have been an autonumber in the first place. If you are using the autonumber as something visible to another person, you are probably mis-using it.
I am enough of a pragmatist to make a limited-case exception on the "making autonumbers visible" restriction. You can use the autonumber as a primary identifier for something that is published (printed, displayed) IF AND ONLY IF you can stand to have the identifier have gaps within its possible range. If the identifier must have ANY OTHER ATTRIBUTES than LONG INTEGER and UNIQUE then you need something other than an autonumber for such a field.