One-Line Exact CAS Fibonacci?

[Joe Horn]

In Home, generating successive members of the Fibonacci Sequence with each press of the Enter key, without using variables, is as simple as this:



However, Home is limited to 12-digit mantissas, so the above is only accurate up to 10^12.

My question is: Is it POSSIBLE to accomplish the same goal (generating successive members of the Fibonacci Sequence with each press of the Enter key, without using variables) in CAS, thereby allowing exact results > 10^12? (The above method fails in CAS because Ans(2) has a different meaning in CAS.) If possible at all, how many ways are there of doing it? If the use of variables is required, can just one variable suffice?

I found a solution that uses the undocumented command 'bloc' but it's fugly and uses two variables that must be initialized first. So I'm eager to see all your clever and non-obvious solutions. ("Just because something is obvious to you, doesn't mean it's obvious to everybody." -- Richard J. Nelson) Have fun!

N.B. Yes, Fibonacci has been discussed MANY times here before, but AFAIK never in terms of the specific goal described above, for the HP Prime.