18885 · 218885 - 1
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At this site we maintain a list of the 5000 Largest Known Primes which is updated hourly. This list is the most important databases at The Prime Pages: a collection of research, records and results all about prime numbers. This page summarizes our information about one of these primes.

This prime's information:

field (help)value
Description:18885 · 218885 - 1
Verification status (*):Proven
Official Comment:Woodall
Proof-code(s): (*):K : Keller
Decimal Digits:5690   (log10 is 5689.22758510345)
Rank (*):79087 (digit rank is 1)
Entrance Rank (*):17
Currently on list? (*):short
Submitted:1987
Last modified:1987
Database id:23258
Status Flags:none
Score (*):30.6903 (normalized score 0)

Archival tags:

There are certain forms classed as archivable: these prime may (at times) remain on this list even if they do not make the Top 5000 proper.  Such primes are tracked with archival tags.
Woodall Primes (archivable *)
Prime on list: yes, rank 13
Subcategory: "Woodall Primes"
(archival tag id 194974, tag last modified 2009-02-12 20:01:30)

Verification data:

The Top 5000 Primes is a list for proven primes only. In order to maintain the integrity of this list, we seek to verify the primality of all submissions.  We are currently unable to check all proofs (ECPP, KP, ...), but we will at least trial divide and PRP check every entry before it is included in the list.
fieldvalue
prime_id23258
person_id9
machineWindows XP P4 1.8GHz
whatprime
notesPrimality testing 18885*2^18885-1 [N+1, Brillhart-Lehmer-Selfridge] Calling Brillhart-Lehmer-Selfridge with factored part 99.93% 18885*2^18885-1 is prime! (10.000000 seconds) PFGW Version 1.1 for Windows Running N+1 test using discriminant 11, base 1+sqrt(11)
modified2003-03-25 11:25:39
created2002-12-09 06:49:36
id33462

Query times: 0.0004 seconds to select prime, 0.0006 seconds to seek comments.