The 12121 Search is a project, which searches for prime numbers of the form: 121 × 2n-1, it also searches for primes of 121 × 2n+1 after being a partner of PrimeGrid. Its sister project, the 2721 Search, searches for primes of 27 × 2n-1.
How to participate
The 12121 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.