From the 5th Drive:

273*2^742930-1 (223647 digits)

My first top-5000 prime
 

7755*2^384196-1 (115659 digits)

Found on 2007 Sept. 22 at 21h37m UTC (search started at n = 330000).

7755*2^n-1 is also prime for n = 2, 3, 8, 10, 14, 17, 22, 29, 38, 47, 54, 55, 87, 96, 106, 175, 204, 224, 232, 321, 380, 444, 446, 539, 567, 729, 776, 825, 1014, 1022, 1135, 1367, 1476, 1622, 1962, 1998, 2184, 2323, 2747, 4675, 4914, 5119, 6317, 6534, 6558, 6687, 6874, 7015, 7252, 7755, 8088, 8795, 10520, 10524, 15931, 17967, 18789, 20034, 22588, 28016, 28834, 30257, 31299, 37547, 38815, 55695, 60844, 66578, 66578, 73814, 74030, 78470, 84996, 85340, 96295, 133755 (checked to n = 143121 so far).

Patrick
 

Congrats on your first prime on the list of Top-5000 largest primes, and welcome to RPS!

52654604145*2^457564-1 (137752 digits)

2145*2^345415-1 is prime (103984 digits)

201*2^775453-1 is prime (233437 digits).
-Curtis

Curtis
 

Nice prime! Much better than those at 600k you were looking for...

new prime for k=137
 

David Broadhurst found 137*2^1849238-1 to be prime (actually in test at Top5000).

he's searching for k=137 and 137137. see his bio-page [url]http://primes.utm.edu/bios/page.php?id=231[/url].
so Cruelty should contact him?!

I am trying to reach him to verify what ranges he has tested. However I am a little bit sad right now, as I've spent some time on sieving it till 37T :sad:

20152491645*2^460155-1 (138531 digits)

3545685*2^349477-1 is prime (105210 digits)