On 10 November 2015, 07:16:15 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=154222 by finding the mega prime:
The prime is 1,461,854 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 51st overall. This is the largest known base 5 mega prime. 35 k's now remain in the Sierpinski Base 5 Problem.
The discovery was made by Scott Brown (Scott Brown) of the United States using an Intel(R) Xeon(R) CPU E5-1620 v3 @ 3.50GHz with 16GB RAM running Windows 10 Professional. This computer took about 5 hours and 5 minutes to complete the primality test using LLR. Scott is a member of the Duke University team.
For more details, please see the official announcement.