Here is a collection of links that I have put together. These links are to websites that I find useful for doing various tasks, and can save you a vast amount of time when stuck looking for something.
This list will keep growing, and if you know of a website that you think should be listed here, please let me know.
pis a prime number. Sadly not all numbers of this form are prime (take 2047=2^11-1 and see for yourself), so this network is devoted to testing very large numbers of Mersenne form to see if they are prime. If your computer plays a part in helping to find a new largest prime number, then you may be in line for a financial reward!