No Prime Left Behind (formerly: PrimeSearch)
(Another of the Prime Pages' resources)
The Largest Known Primes Icon
  View this page in:   language help
project A titan, as defined by Samuel Yates, is anyone who has found a titanic prime. This page provides data on those that have found these primes. The data below only reflect on the primes currently on the list. (Many of the terms that are used here are explained on another page.)

g190, g193, g219, g263, g314 ... ... L3055, L3844, L3870, L3994, L4076
E-mail address:
Web page:
Username: NPLB (entry created on 07/20/2003)
Database id:518 (entry last modified on 12/02/2016)
Active primes:on current list: 184, rank by number 4
Total primes: number ever on any list: 3993
Production score: for current list 49 (normalized: 332), total 50.5323, rank by score 8
Largest prime: 319 · 22498685 - 1 ‏(‎752182 digits) via code L2017 on 10/07/2018
Most recent: 427 · 21577169 - 1 ‏(‎474778 digits) via code L3994 on 10/13/2018
Entrance Rank: mean 1567.32 (minimum 92, maximum 2856)

Descriptive Data: (report abuse)
The PrimeSearch project was originally created by Michael Hartley to search for primes of the form k*2^n-1 (Riesel primes) for k=300-1001 up to n=600K.

In Jan. 2008, the project was expanded by the "No Prime Left Behind" (NPLB) project at the site. The intent now is to find Riesel primes that have not been found by others (or otherwise left behind) in a much larger n-range than the original PrimeSearch project. This includes mostly top-5000 efforts but from time-to-time can include non-top-5000 and/or double-check efforts.

New searches are currently being conducted for k=300-1001 for 100's of k's at once and occassional double-checking is ongoing at lower n-ranges.

Coordinated team drives, automated PRPnet processing, and well-sieved files already available make finding primes very quick and easy for both novices and experienced prime searchers alike. Sieved files are also available for those who like to search their own k's or who like to search for primes offline in a less-automated fashion.

I administer No Prime Left Behind (formerly: PrimeSearch) and I would like to
Edit this page
Surname: NPLB (used for alphabetizing and in codes)
Unverified primes are omitted from counts and lists until verification completed.