Will Edgington and I try to keep our tables of Mersenne factorizations up to date by synchronizng every week or so. The latest indicated that another Mersenne number had been completely factored. Neither Will nor I have the resources at the moment to prove the 2193-digit cofactor of M(7417) is prime. It's certainly a strong pseudoprime.

If anyone would care to complete the proof, please let Will and me know the result. The known prime factors of M(7417) are 118673, 16269026327 and 3888241452787718190543521.

Apologies for not crediting the person who found the largest of the three factors given above. I don't know who he or she is.

Paul