- Hi group,

138^196873-137^196873 is PRP for bases 2, 3, 5, 7, 11, 13, 17, 19, 31, 71 and 101.

This number has 421285 digits.

Moreover, 138^p-137^p is composite for all primes p < 196873 !

This later result should however better be double checked, since it took me more than 2 years to check all p <= 196873; and I can't be absolutely sure I made no mistake during this long period.

Any volunteer for the double check task ? ;-)

Best regards,

Jean-Louis - --- In primenumbers@yahoogroups.com, "j_chrtn" <j_chrtn@...> wrote:
>

Sterling work, Jean-Louis!

> Hi group,

>

> 138^196873-137^196873 is PRP for bases 2, 3, 5, 7, 11, 13, 17, 19, 31, 71 and 101.

>

> This number has 421285 digits.

>

> Moreover, 138^p-137^p is composite for all primes p < 196873 !

>

> This later result should however better be double checked, since it took me more than 2 years to check all p <= 196873; and I can't be absolutely sure I made no mistake during this long period.

>

> Any volunteer for the double check task ? ;-)

(David should like this:-)

Mike