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Old 2005-03-22, 15:35   #317
Kosmaj
 
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Nov 2003

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Finally I hit a big one:

21*2^999599-1 is prime! 310911 digits
currently the 80th largest of all times

After testing k=21 from 500k to 950k in increasing order I decided to try the top range from 1M to 995k in reversed order and the prime was right there on line 7 of the file!

Achieved limits of this and other k's (no other primes found):
k=7: 1.180 M
k=21: 950k
k=55: 430k
k=77: 700k
k=79: 520k stopped
k=89: 500k

Continuing k=55 and k=89 to 520k, k=21 to 1M, k=7 and k=77 until further notice
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