>From: [EMAIL PROTECTED]
>Date: Sun, 7 Mar 1999 16:12:07 -0000
>Subject: Re: Mersenne: Category 1,2 or 3 ?
>
>Gordon Spence writes:
>
>>>>What bothers me most I guess is that the ordinary humble joe in the street
>>>>being realistic has no chance whatever of finding the next mersenne prime.
>
>This is a slight exaggeration. If you're running LL tests or double-checks
at all, 
>you've more chance than if you're not.

True if I buy just one ticket I have a chance, but if you have 10,000
tickets me thinks you have a greatly improved chance (though still
statistically improbable)

[snip]

> Therefore there is about 1 
>chance in 100 that another Mersenne prime less than Spence's Number
remains to be 
>found.

I never actually worked out the figures, but something must have sunk in at
some level of (un)consciousness, I have stopped doing any factoring work
now (hardly get any 'credit' for doing it) and have turned over 6 machines
to double checking leaving just 4 at LL testing.

[snip]

>1. Does anyone know where the estimate of an exponent yielding a Mersenne
prime 
>that Prime95 outputs in its status pop-up comes from? (George, I can see & 
>understand th
e source code, what I would like to know is the source of the 
>algorithm)

Very good question, I often wondered that. BTW I am testing M20295673 at
home. Apparent I have odds of about 161,000 to 1 that it is prime.

>
>2. Does our continued effort in eliminating possible Mersenne primes
change that 
>estimate in any way? Since I joined the project 10 months ago, we have
found no 
>new Mersenne primes (any day now?) but eliminated a great many exponents, 
>nevertheless the formula doesn't seem to have changed, which it probably
should 
>have done if it's (even partly) based on empirical data.

Intuition says that it should. But is this a variation on the old
coin-tossing problem that is counter intuitive?

regards

G



Gordon Spence,                             Nokia IP Telephony
Applications Engineer                      Grove House, Waltham Way,
[EMAIL PROTECTED]                      White Waltham, Maidenhead,
http://www.nokiaiptel.com/                 Berkshire, SL6 3TN,  UK.

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