Largest Known Prime Number discovered

[Gerson W. Barbosa]

(01-07-2018 07:23 PM)Gerson W. Barbosa Wrote:  My HP-50g can evaluate M4253 (2^4253 - 1) in less than 30 seconds,
...
4253

« 1 DUP ROT
START DUP +
NEXT 1 -
»

EVAL
...
PS: M23209, discovered in 1979, takes about 333 seconds (6987 digits long).

Actually the first example can be evaluated in less than 5 seconds by doing simply 2 4253 y^x 1 -. The second example, however, causes the calculator to return an error message ( ^ Error: Integer too large ).

It's interesting to notice how execution is slowed down when DUP + is replaced with 2 * (2 SWAP * is better, but still worse than DUP + ).

It appears M216091 (65050 digits) is the most we can get on the 50g (642.4 seconds on the emulator, perhaps about 7 hours on the calculator).