Hundred Million Digit Almost Prime
After 4761 hours of computation, I proved that 2382242031-1 is not a prime.
There is an ongoing search for large primes, with a prize awarded to the discovery of the first prime of one hundred million digits. So I got busy, and performed the Lucas-Lehmer primality test on my powerful GPU. The computation was performed in my spare time, running the CUDA process during idle times since April, finishing now in February. In total, 198 computer-days were spent performing this check over a period of 301 days.
Better luck next time!