Re: Mersenne: Zip Codes
Is there anything geographically special about your old town? On Fri, 17 Dec 1999, Vincent J. Mooney Jr. wrote: Also since the list is quite quiet, my old zip code of 21701 is a Mersenne prime. Are there any other zip codes that are Mersenne primes? I don't know how to look up 02203 or 02281 for example. _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers -- ~~~ : WWW: http://www.silverlink.net/poke : : E-Mail: [EMAIL PROTECTED] : ~ :It will be noisy, it will be scary and it will not be mistaken for a VFW parade! : ~ _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: v19 and priorities
On 17 Dec 99, at 16:35, Gordon Bower wrote: Something strange happened, though. Version 19 slows down considerably more in response to my doing other low-demand things on my machine, reading email/web browsing/etc. Is this just in the nature of v19, something to do with the optimizations that were added to speed it up? (It does still average a faster rate in the long run). Very likely this is the case. The new code is better tuned to the hardware - making more efficient use of the cache - if something else makes demands on the same cache, there's bound to be a hit of some sort. I would guess that with a moderate load of active "normal" applications on the system, v18 v19 would run at about the same speed. Of course, v19 would slow down more since it's starting at a faster speed. As long as I am writing to the list -- perhaps someone could explain in a little more detail than readme.txt does as to what the valid range of values for the Priority variable are and what the effect of each is on NT and 95? I experimented a little by trial and error last summer when a friend running a 3-D screen saver offered to let me run the program on his machine, but we never had much success fine-tuning it so as to not interfere with his work. The valid range is 0-15. If you specify 0, you will lose half your CPU to the OS's native cycle sink. This is probably not what you want. Screen savers normally run at priority 4, normal applications at 8. If you set a CPU-intensive program to run above priority 8, your "normal" activities will be badly impacted. If you go above 10 or 11, you can expect to start to get problems with device drivers for modems etc. If you try 14 or 15, you will very likely lose control of your system altogether. If you really need to run a screensaver as well as Prime95, I'd reccomend setting Prime95 at priority 4 so that it shares cycles about equally with the screensaver. Regards Brian Beesley _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Mersenne: Fibonacci Series
An old book of mine gives without proof an example of Fibonacci Sequence that countains no primes, but where U(1) and U(2) are co-prime. The sequence was found by R. L. Graham. Reference : "A Fibonacci-like sequence of composite numbers", R.L. Graham, Math. Mag. 37, 1964. U(1) = 1786772701928802632268715130455793 U(2) = 1059683225053915111058165141686995 U(N+2) = U(N+1) + U(N) I only verified with Mapple that U(1) and U(2) are co-prime and that U(N) is composite for N10. On Fri, 17 Dec 1999, Griffith, Shaun wrote: Ian McLoughlin wrote: Since the list is quiet... Does a Fibonnacci series contain a finite or an infinite number of primes? From what I understand.. In a gen.F sequence if the first two numbers are divisible by a prime all its numbers are divisible by the same prime, if the first two numbers are co-prime is there a generalised sequence that contains NO PRIMES The generalized Fibonacci sequence seems to generate at least one prime regardless of the values assigned to Fib(1), Fib(2), *unless* Fib(1) and Fib(2) are even. Then there is never an odd number, and never a chance for a If they are both even they aren't coprime. :) prime after Fib(2) (though Fib(1) or Fib(2) may be =2, but that seems trivial). I tried it with composite odd numbers, such as 15,77, which happen to be coprime. The first 3 primes generated are Fib(7)=691, Fib(14)=20101, and Fib(28)=16945081. _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: Fibonacci Series
At 04:50 PM 12/18/99 +0100, François Perruchaud wrote: An old book of mine gives without proof an example of Fibonacci Sequence that countains no primes, but where U(1) and U(2) are co-prime. The sequence was found by R. L. Graham. Reference : A Fibonacci-like sequence of composite numbers, R.L. Graham, Math. Mag. 37, 1964. U(1) = 1786772701928802632268715130455793 U(2) = 1059683225053915111058165141686995 U(N+2) = U(N+1) + U(N) I only verified with Mapple that U(1) and U(2) are co-prime and that U(N) is composite for N10. I checked a few thousand terms, and they were all composite. ++ | Jud McCranie | | | | 137*2^197783+1 is prime! (59,541 digits, 11/11/99) | ++
Re: Mersenne: Fibonacci Series
Hi folks U(1) = 1786772701928802632268715130455793 U(2) = 1059683225053915111058165141686995 U(N+2) = U(N+1) + U(N) I checked a few thousand terms, and they were all composite. There is almost certainly a 'covering set' of divisors. In essence you need to find a set of primes P and a modulus M, then prove that U(N) has a factor in P specified by the value of N mod M. Chris Nash Lexington KY UNITED STATES _ Unsubscribe list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
