No Prime Left Behind (formerly: PrimeSearch)

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 reflects on the primes currently on the list. (Many of the terms that are used here are explained on another page.)

Proof-code(s):

E-mail address:

gbarnes017

(at)

gmail

(dot)

com

Web page:

http://www.mersenneforum.org/forumdisplay.php?f=82

Username

NPLB

(entry created on 7/21/2003 01:51:19 UTC)

Database id:

518

(entry last modified on 2/1/2026 18:02:59 UTC)

Active primes:

on current list: 62, rank by number 5

Total primes:

number ever on any list: 4659

Production score:

for current list 50 (normalized: 110), total 52.3452, rank by score 8

Largest prime:

1871 · 2^7207954 - 1 ‏(‎2169814 digits) via code L6283 on 9/26/2025 23:19:25 UTC

Most recent:

449 · 2^2975236 - 1 ‏(‎895638 digits) via code A76 on 3/29/2026 11:46:43 UTC

Entrance Rank:

mean 3039.21 (minimum 300, maximum 4954)

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 mersenneforum.org site. The intent now is to find Riesel primes that have not been found by others (or otherwise left behind) in a much larger k and n-range than the original project. This includes mostly top-5000 efforts but from time-to-time can include non-top-5000 and/or double-check efforts.

Searches are currently being conducted for k<=1001 for 100's of k's at once on many different drives.

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.

Surname: NPLB (used for alphabetizing and in codes).
Unverified primes are omitted from counts and lists until verification completed.

I administer No Prime Left Behind (formerly: PrimeSearch) and I would like to