"Brian J. Beesley" <[EMAIL PROTECTED]> writes
>In case anyone else notices that F25 is an "interesting" size -
>10,100,891 digits - could I save you a whole bundle of time by
>remarking that F25, F26 and F27 are all known to be composite, we
>know at least one factor of each of them.
The cofactor of F25 (after dividing out all the known factors) is
currently 'status unknown', isn't it?.
So it might be worth testing for compositeness. However at present there
seems to be no way of proving it prime if it fails the compositeness
test.
--
Tony
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