*** SEARCH FOR NINE CONSECUTIVE PRIMES IN ARITHMETIC PROGRESSION *** *** NEWSLETTER/2 *** 23 November 1997 Hello again, *** NEW VERSION OF THE WINDOWS PROGRAM *** Version 2.19 of CP09 is now ready. It's a little faster than 2.18 due mainly to better organization of data. A small bug has been corrected. You can download it from http://www.ltkz.demon.co.uk/ar2/cp09v219.zip We decided it was not useful to create a special version for W95 and NT. *** NEW VERSION OF THE UNIX PROGRAM *** Paul Zimmermann has already announced version 3 of the Unix program which can be downloaded from his site at http://www.loria.fr/~zimmerma/records/9primes.html The main differences are: - it now loops automatically on a very large range (you don't need any more to start it from a shell-script or from MuPAD) - it is much faster than the previous version (2). In addition, he has spent more time to determine the optimal parameters to use for each type of machine. The default was definitely too large. Here are the new optimal 2nd and 3rd parameters: DecAlpha: 10000000 4000000 1860M/h (275Mhz) PC/Linux: 600000 3000000 900M/h (200Mhz) Solaris: 2500000 7000000 719M/h IRIX64: 10000000 6000000 3114M/h (R10000) IRIX: 10000000 4000000 410M/h (R4000, 5.3) hpux 1250000 4000000 1550M/h It looks as if a little friendly rivalry has paid off. Unix has caught up with PC. The improvement is dramatic and the full power and might of the 64-bit Alpha can now be brought to bear on the problem. *** PROGRESS *** Here is a summary of progress to date. More details can be found at http://www.loria.fr/~zimmerma/records/progress.html We now have a total of nine "near misses": 9 primes in A.P. (Paul Zimmermann) R 9 220214727578475 ap=9 cp=4 [-1:C.P.P.P.P*P*P.P*P.P.C:+9] 9 primes in A.P. (Paul Zimmermann) R 9 221153832755059 ap=9 cp=7 [-1:C*P.P.P.P.P.P.P*P*P*C:+9] 9 primes in A.P. (Torsten Metzner) R 9 226139828468252 ap=9 cp=5 [-1:C.P*P.P*P*P.P.P.P.P*C:+9] 9 primes in A.P. (Michel Quercia) R 9 233009952168708 ap=9 cp=5 [-1:C.P.P.P.P.P*P*P*P*P*C:+9] 9 primes in A.P. (Michel Quercia) R 9 233319609748154 ap=9 cp=4 [-1:C*P.P.P.P*P*P.P.P*P*C:+9] 9 primes in A.P. (Michel Quercia) R 9 233571893912031 ap=9 cp=2 [-1:C*P.P*P.P*P*P.P*P.P.C:+9] 9 primes in A.P. (Harvey Dubner) R 9 400000508797243 ap=9 cp=5 [-1:C*P*P.P.P.P.P*P.P.P*C:+9] 9 primes in A.P. (Harvey Dubner) R 9 402224283386010 ap=9 cp=5 [-1:C.P.P.P.P.P*P.P*P*P.C:+9] 9 primes in A.P. (Hubert Fauque) R 9 415050637639089 ap=9 cp=4 [-1:C*P*P.P.P.P*P.P.P.P*C*+9] and three "near hits": 8 consecutive primes in A.P. (Paul Zimmermann) R 8 221236230528997 ap=8 cp=8 [-1:C*P.P.P.P.P.P.P.P.C.C*+9] 8 consecutive primes in A.P. (Paul Zimmermann) R 8 220237184434352 ap=8 cp=8 [-1:C.P.P.P.P.P.P.P.P.C*C:+9] 8 consecutive primes in A.P. (Sturle Sunde) R 8 228862441305057 ap=8 cp=8 [-1:C*P.P.P.P.P.P.P.P.C.C:+9] *** REPORTING PROGRESS *** Now that quite a few days have elapsed, can I ask everyone for some feedback. If you do have any results, either nine primes, or eight consecutive primes, can you please report them either to Tony Forbes or to Harvey Dubner. I (TF) am aware of the noticeable (to me) absence of the 300 trillions from the above list. That's the area where I and my helpers are searching. I haven't found anything. Has anyone else? *** BUGS *** I had a bug report from Luke Welsh. CP09 stopped with a message "Invalid parameter in imod call." We both agree it must have been a one-off hardware glitch. It's interesting to hear about these but I think it's worth pointing out that it doesn't really matter if CP09 (or Paul's program) works for only 99.99 percent of the time. We are only interested in finding a specific object, namely a set of 9 consecutive primes in A.P. Unlike projects such as GIMPS, there are no "negative" results to collect. *** Best wishes and good luck, Harvey Dubner <70372.1170@compuserve.com> Tony Forbes Paul Zimmermann