PrimeForm e-group has found the largest known Chen prime:
(1284991359*2^98305+1)*(96060285*2^135170+1)-2
2^98305 divides N+1 which enables a BLS proof:
D:>pfgw -tp -q"(1284991359*2^98305+1)*(96060285*2^135170+1)-2"
PFGW Version 1.2.0 for Windows [FFT v23.8]
Primality testing (1284991359*2^98305+1)*(96060285*2^135170+1)-2
[N+1, Brillhart-Lehmer-Selfridge]
Running N+1 test using discriminant 5, base 1+sqrt(5)
Calling Brillhart-Lehmer-Selfridge with factored part 42.10%
(1284991359*2^98305+1)*(96060285*2^135170+1)-2 is prime!
(6253.7959s+0.0222s)
Congratulations to Micha Fleuren who got the hit after bad e-group luck,
some of it on larger candidates.
The other PRP testers were Jens Kruse Andersen, Pierre Cami, Jason Earls,
Andy Klingeleers, Paul Underwood, Thomas Wolter.
PrimeForm/GW performed the PRP tests.
Phil Carmody made chenpq2 which trial factored to 2^31.
Thanks to all participants.
Also thanks to Chris Caldwell for maintaining the Prime Pages database.
Without it we might not have resources to find a BLS provable Chen.
The database says:
1284991359*2^98305+1, David Underbakke and Phil Carmody in 2001.
96060285*2^135170+1, David Underbakke with Yves Gallot's Proth.exe in 2002.
3 coincidences (maybe not big if the database is examined):
The same person (Underbakke) found both primes.
Phil Carmody who wrote the Chen sieve also contributed to one of them.
Both primes were found in old twin searches and now they combine to
beat the current twin record as largest known Chen.
Paul: I will suggest a bio text later.
Micha: You can submit with credit to PrimeForm and egroup.
You can try adding the comment Chen and see whether Chris tolerates it.
In the weekend I will mail MathWorld with a suggested article on Chen primes.
Guess whether the record will be mentioned ;-)
I will also submit it to
http://en.wikipedia.org/wiki/Chen_prime
--
Jens Kruse Andersen