On 18 January 2018, 19:39:18 UTC, PrimeGrid’s Generalized Cullen/Woodall Prime Search found the largest known Generalized Cullen prime:
Generalized Cullen numbers are of the form: n*b^n+1. Generalized Cullen numbers that are prime are called Generalized Cullen primes. For more information, please see “Cullen prime” in The Prime Glossary (http://primes.utm.edu/glossary/xpage/Cullens.html).
The prime is 2,732,038 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 1st for Generalized Cullen primes and 30th overall.
Base 116 was one of 13 prime-less Generalized Cullen bases below b=121 that PrimeGrid is searching. The remaining bases are 13, 25, 29, 41, 47, 49, 55, 69, 73, 101, 109 & 121.
The discovery was made by Scott Brown (Scott Brown) of the United States using an Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz with 4GB RAM, running Windows 10 Enterprise Edition. This computer took about 8 hours and 34 minutes to complete the primality test using multithreaded LLR. Scott is a member of the Aggie The Pew team.
The prime was verified on 19 January 2018 17:24:17 UTC by Serge De Saffel (lentosy) of Belgium using an Intel(R) Core(TM) i5-6600K CPU @ 3.50GHz with 16GB RAM, running Windows 10 Education Edition. This computer took about 15 hours 22 minutes to complete the primality test using LLR. Serge is a member of the team Sicituradastra.
For more details, please see the official announcement.