The 27121 Search, a part of PrimeGrid, is a Distributed computing project, which searches for prime numbers of the form: 27 × 2n ± 1 and 121 × 2n ± 1.
How to participate
The 27121 site features a brilliant reservation system, which makes it easy to use PRPclient to reserve a testing number directly from the website.
Then this application will use LLR or PFGW to test this testing number and afterwards submit the result back via the website.
The 27121 Search has currently 12 primes in the The Prime Pages. The bigger primes are 27 × 21902689-1 and 27 × 22218064+1, which weighs in at 572768 digits and 667706 digits, found on 2009-12-10 and 2009-12-23.