# The 'No Prime Left Behind' Project (NPLB)

### Project Information:

This project searches for Riesel primes of the form k · 2 ^{n} - 1 with odd k and

300 < k __<__ 1001 and n > 260.000 not reserved by others with highly presieved ranges.

This project was founded with the intention of managing and continuing the PrimeSearch-Project
(to be found here)

in a more interesting manner for everyone. There are efforts for both lone searchers and for coordinated team efforts,

which results in a higher precision of prime reporting.

For more information visit the forum Software/Instructions/Questions.

Some scoring statistics are also available with found primes and completed ranges by contributors (have to be updated)!

### Background Information:

PrimeSearch was set up by Michael Hartley in 2001 for the search of prime numbers of the form k·2^{n}-1

with 255 __<__ k __<__ 1001 and 16000 < n __<__ 600000. The range for k < 255 was added in 2007.

Some reasons for creating a project like NPLB:

- Every reserved range (in n=20k chunks) had to be sieved by the contributor himself.
- PrimeSearch only collected primes without any test results so there were many missing or incorrect primes.
- There was no forum helping the contributors with problems or questions and coordinating their search.
- Recently there have been 'contributors' at PrimeSearch filling in primes that were obtained from other sites obviously

without doing any actual testing so useless anyway.

Gary Barnes decided to change all these deficiencies and begun to sieve 400 __<__ k __<__ 1001 from n = 260000 to 600000 in 2007.

Independently also in 2007 Karsten Bonath begun to sieve and test a range of 100 k's with k > 300.

So just a matter of time NPLB was born.

**On Jan 21, 2008 this project started with a forum here.**

### Detailed Search Information:

**Team Drives:**

At first there are three different ranges for 400 < k __<__ 1001 for searching with the following conditions:
The whole range from n = 260000 to 600000 was presieved up to p = 5·10^{12} (= 5 Trillions = 5 T).

**Races:**

See the Races-Overview!
### Future Information:

#### 300 < k < 400:

This range will be added when the sieving is done. Some of those k's will be left for individual searching.

Additional searches may begin above n = 600000 for k's previously searched to that limit.

#### Double-checking of 300 < k __<__ 1001 for n = 100000 to 260000:

Double-checking has already been completed for this k-range for n __<__ 100000 in 2007 by Gary Barnes.

Many missing primes and errors were found there.

#### Double-checking of n = 260000 to 600000 for already completed k-values:

This is being run in conjunction with the main team drive.

### Goals for this project:

- End 2009: All 300 < k
__<__ 1001 tested up to n = 600000.
- In 2009: Begin of sieving the same k-range for 600000
__<__ n __<__ 1000000.
- End 2010: k-range doublechecked up to n = 260000.
- End 2012: k-range tested up to n = 1000000

## And now...

### Thanks and come join us for the fun at No Prime Left Behind!