Nothing Special   »   [go: up one dir, main page]

Sexy Prime

Download as pdf or txt
Download as pdf or txt
You are on page 1of 3

Sexy prime

In mathematics, sexy primes are prime numbers that differ from each other by six. For example, the numbers 5 and 11 are both sexy
primes, because 11 minus 5 is 6. If p + 2 or p + 4 (where p is the lower prime) is also prime, then the sexy prime is part of a prime
triplet.

The term "sexy prime" is a pun stemming from theLatin word for six: sex.

Contents
n# notation
Types of groupings
Sexy prime pairs
Sexy prime triplets
Sexy prime quadruplets
Sexy prime quintuplets
See also
References
External links

n# notation
As used in this article,n# stands for the product 2 · 3 · 5 · 7 · … of all the primes ≤n.

Types of groupings

Sexy prime pairs


The sexy primes (sequences A023201 and A046117 in OEIS) below 500 are:

(5,11), (7,13), (11,17), (13,19), (17,23), (23,29), (31,37), (37,43), (41,47), (47,53), (53,59),
(61,67), (67,73), (73,79), (83,89), (97,103), (101,107), (103,109), (107,113), (131,137),
(151,157), (157,163), (167,173), (173,179), (191,197), (193,199), (223,229), (227,233),
(233,239), (251,257), (257,263), (263,269), (271,277), (277,283), (307,313), (311,317),
(331,337), (347,353), (353,359), (367,373), (373,379), (383,389), (433,439), (443,449),
(457,463), (461,467).

As of May 2009 the largest known sexy prime was found by KenDavis and has 11,593 digits. The primes are (p, p+6) for

p = (117924851 × 587502 × 9001# × (587502 × 9001# + 1) + 210) × (587502 × 9001# −


1)/35 + 5.[1]

9001# = 2×3×5×...×9001 is aprimorial, i.e., the product of primes ≤ 9001.

Sexy prime triplets


Sexy primes can be extended to larger constellations. Triplets of primes (p, p + 6, p + 12) such that p + 18 is composite are called
sexy prime triplets. Those below 1000 are ( A046118, A046119, A046120):

(5,11,17), (7,13,19), (17,23,29), (31,37,43), (47,53,59), (67,73,79), (97,103,109),


(101,107,113), (151,157,163), (167,173,179), (227,233,239), (257,263,269), (271,277,283),
(347,353,359), (367,373,379), (557,563,569), (587,593,599), (607,613,619), (647,653,659),
(727,733,739), (941,947,953), (971,977,983).

As of 2013 the largest known sexy prime triplet, found by Ken Davis had 5132 digits:

p = (84055657369 · 205881 · 4001# · (205881 · 4001# + 1) + 210) · (205881 · 4001# - 1) / 35


+ 1.[2]

Sexy prime quadruplets


Sexy prime quadruplets (p, p + 6, p + 12, p + 18) can only begin with primes ending in a 1 in their decimal representation (except for
the quadruplet with p = 5). The sexy prime quadruplets below 1000 are ( A023271, A046122, A046123, A046124):

(5,11,17,23), (11,17,23,29), (41,47,53,59), (61,67,73,79), (251,257,263,269),


(601,607,613,619), (641,647,653,659).

In November 2005 the largest known sexy primequadruplet, found by Jens Kruse Andersen had 1002 digits:

p = 411784973 · 2347# + 3301.[3]

In September 2010 Ken Davis announced a 1004-digit quadruplet withp = 23333 + 1582534968299.[4]

Sexy prime quintuplets


In an arithmetic progression of five terms with common difference 6, one of the terms must be divisible by 5, because 5 and 6 are
relatively prime. Thus, the only sexy prime quintuplet is (5,11,17,23,29); no longer sequence of sexy primes is possible.

See also
Cousin prime (two primes that differ by 4)
Prime k-tuple
Twin prime (two primes that differ by 2)

References
1. Ken Davis, "11,593 digit sexy prime pair"(http://tech.groups.yahoo.com/group/primenumbers/message/20207)
.
Retrieved 2009-05-06.
2. Jens K. Andersen, "The largest known CPAP-3" (https://web.archive.org/web/20130502162216/http://users.cybercity
.
dk/~dsl522332/math/cpap.htm#k3). Retrieved 2014-06-13.
3. Jens K. Andersen, "Gigantic sexy and cousin primes"(https://groups.yahoo.com/group/primeform/message/6637)
.
Retrieved 2009-01-27.
4. Ken Davis, "1004 sexy prime quadruplet"(http://tech.groups.yahoo.com/group/primenumbers/message/21783)
.
Retrieved 2010-09-02.

Weisstein, Eric W. "Sexy Primes". MathWorld. Retrieved on 2007-02-28 (requires compositep+18 in a sexy prime
triplet, but no other similar restrictions)

External links
Grime, James. "Sexy Primes (and the only sexy prime quintuplet)"
. Numberphile. Brady Haran.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Sexy_prime&oldid=865866559


"

This page was last edited on 26 October 2018, at 18:01(UTC).

Text is available under theCreative Commons Attribution-ShareAlike License ; additional terms may apply. By using this
site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of theWikimedia
Foundation, Inc., a non-profit organization.

You might also like