For a number of years (starting from v19.0 ofPrime95 (Oct. 1999) up to Sept. 2008)GIMPS /PrimeNet limited the range ofexponents that were available for assignment/testing to a maximum of ~79.3 million. This seemingly odd number is derived from the fact that it is the largest to practically test using anFFT size of 4096K. The size limit of the FFT used came about because of limitations of thecomputer systems thatPrime95 was designed to run on.
Exponents larger than 79.3 million had been worked on (mainlytrial factoring, like the100 Million Digit Prefactor Project) prior to Sept. 2008 (outside of PrimeNet), using programs other than Prime95. The results of these test were often forward toGeorge Woltman andWill Edgington. When PrimeNet v5 was rolled out, exponents up to 1,000,000,000 were suppported. All of the work that had been previously reported to Woltman, was included in the data on PrimeNet.
