Hello David,

At 02:18 PM 2/12/2010, djbroadhurst wrote:

>--- In primenumbers@yahoogroups.com,

>"djbroadhurst" <d.broadhurst@...> wrote:

>

> > Here's a plupluperfect chain of 8:

> >

> > p=3;for(k=1,9,print([k,factor(p)]);p=140820*p-422453)

> > [1, Mat([3, 1])]

> > [2, Mat([7, 1])]

> > [3, Mat([563287, 1])]

> > [4, Mat([79321652887, 1])]

> > [5, Mat([11170075159124887, 1])]

> > [6, Mat([1572969983907966164887, 1])]

> > [7, Mat([221505633133919795338964887, 1])]

> > [8, Mat([31192423257918585579633034964887, 1])]

> > [9, [7, 1; 627502434740013603046274854822137841, 1]] \\ Bounded!

>

>Puzzle 11: Find a plupluperfect chain of 12, i.e. a triplet

>(A, B, p[1]) such that A = 1 mod 11, B is coprime to 11,

>and the iteration p[n+1] = A*p[n] + B yields a chain of

>12 increasing primes, p[n], for n = 1 to 12.

>

>Comments: Clearly, p[2] = 11 and hence B = 11 - A*p[1], with

>p[1] = 2, 3, 5 or 7. So this boils down to 4 sub-problems of

>Carmody-scale difficulty (maybe easy for Phil; harder for mere

>mortals like Kevin, Mike, or me). I did not yet find a solution.

>

>David

I won't jump into this one just yet. I'm turning over about 56000

8/16 chains per hour currently for Puzzle 2. My hope is that I'll

get one 16/16 per 8^8 8/16 and find another five 15/16 chains on the way.

I had a quick check though, but my current script doesn't lend itself

to pluperfect chains let alone plupluperfect.

Best Regards,

Kevin.