This is a simple Java program, so you will need to download jdk (any version 1.3.1 or higher should work fine) from
Sun's website. I assume that if you are running Linux or Mac, you will know
what to do with the .class and/or the .java files. The program is fairly self explanatory.
However, if you need any more help, or if you are using Windows and aren't sure what you need to do, here are some
I'm guessing that you probably are only interested in the program itself, and not the actual source code, so you only want to deal with the first link above. Right click on it and select "Save Target As..." and save the file to the "bin" folder in the "jdk" folder (what you downloaded off Sun's website).
Open up a command prompt, and navigate to the "bin" folder using the "cd" (change directory) command. For instance, if the command prompt line said "C:\" and I had the jdk1.3.1 folder in the C:\ directory, I would type "cd jdk1.3.1\bin".
Once you have navigated to the proper directory, type "java Crossnumber". This will run the program. Anytime you want to rerun the program, just type this phrase in again (in certain versions of windows, you can press the up arrow key to reach previous commands so you don't have to type them in again). If you ever wish to cancel the program while it's running, just press CTRL-C.
The program asks you to enter a value for p (a prime greater than 2), and then a value for q (a prime greater than p). It also gives you an option of using the default lower bound on the cross numbers (which is pq), or setting a different lower bound. The new lower bound B must satisfy the following inequality:
pq <= B <= 2pq-p-q+1
The program then will calculate the values, and generate two files in your "bin" directory: "Crossnumbers p q.txt" and "Min Zero Seq p q.txt". The first file lists the values of p and q, and then the contiguous blocks of cross numbers that are not in W_pq, which will be displayed in a manner similar to the other program on this page. The second file also lists the values of p and q, but then it lists a family of minimal zero sequences, with the values a, b, and c listed for each sequence. The "a" represents the number of terms in the sequence of order p, the "b" represents the number of terms in the sequence of order q, and the "c" represents the number of terms in the sequences of order pq. As explained on the previous page, only sequences that contain an occurence of the element 1 are generated in this file.