Hello David,

At 09:43 AM 3/01/2011, djbroadhurst wrote:

>--- In primenumbers@yahoogroups.com, Kevin Acres <research@...> wrote:

> > after now having found 17 15/16 chains, should

> > I reasonably be expecting a 16/16 some time soon?

>

>Suppose that you guessed a 1/9 chance. Then the odds

>of /not/ getting a result after 17 tries are

>exp(-17/9) =~ 15%

Thanks for that. It will give me some idea of what to hope for at least.

Right now I'm trawling shallow waters again. This gives me faster

processing and a greater 15/16 density. Over the next couple of days

I'm going to take b up to just less than 2^31 with x < 51561510. I

expect this to give an extra 6 or so 15/16 chains on top of the 18 I have now.

The current state of my search is:

0 < b < 506306000, 0 < x < 511020510 -> completed

506306000 < b < 1000479680, 0 < x < 51561510 -> completed

1000479680 < b < 1600328930, 0 < x < 51561510 -> 50% complete (~17

hours to go)

1600328930 < b < 2147085140, 0 < x < 51561510 -> not yet started (~32 hours)

For completeness, my 18th 15/16 is:

[18*x + 1220760325, [38738527, 15]]

Best Regards,

Kevin.