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Old 2011-08-03, 15:11   #10
LiquidNitrogen
 
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Jun 2011
Henlopen Acres, Delaware

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Quote:
Originally Posted by CRGreathouse View Post
If you reduce mod the Mersenne number at each step, you can prove 2^19 - 1 prime in Excel.
I'm not sure I follow. Here is what I did.

1. Proving p = 2^n - 1 is prime for n = 5, p = 31.
2. S(0) = 4 {defined}
3. Need to generate up to S(n-2) where S(x+1) = [S(x) * S(x)] - 2

3a. S(1) = 4^2 - 2 = 14
3b. S(2) = 14^2 - 2 = 194
3c. S(3) = 194^2 - 2 = 37634

4. Test S(n-2)/p = S(3)/p = 37634/31. If remainder is 0, p is prime.

37634/31 = 1214.0 so p is prime.

What would this involve doing it the way you mentioned?

Last fiddled with by LiquidNitrogen on 2011-08-03 at 15:18
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