Welcome to the 321 Prime Search

A 321 (or Thabit) number is in the form of 3*2^n-1. A 321 number of the second kind is in the form 3*2^n+1. PrimeGrid is searching for primes in both forms. These numbers have been studied by mathematicians since Thābit ibn Qurra in the 9th century.

Originally, 321 primes were being searched for by the 321 Search Project. PrimeGrid completely took over the search in 2008.

Further reading:
List of Ns for which 3*2^n-1 is prime
List of Ns for which 3*2^n+1 is prime
Thabit Number on Wikipedia

Primes found at PrimeGrid:
3*2^11895718-1
3*2^11731850-1
3*2^11484018-1
3*2^10829346+1
3*2^7033641+1
3*2^6090515-1
3*2^5082306+1
3*2^4235414-1
3*2^2291610+1