## Easily memorized primes

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• This is more or less a fun thread. However, it can occasionally be handy to give a concrete example of a large prime to friends, etc. None of these are
Message 1 of 16 , Aug 30, 2009
This is more or less a "fun" thread. However, it can occasionally be
handy to give a concrete example of a large prime to friends, etc.
None of these are particularly large, but they are easier to memorize
(for whatever reason) than most primes in their size range.

Here's a couple candidates:

8,675,309 (and 8,675,311 - twin primes)
1,000,003
10^700+7
10^999+7
4,001

Nathan
• 2221!11+1
Message 2 of 16 , Aug 31, 2009
2221!11+1
--- In primenumbers@yahoogroups.com, Nathan Russell <windrunner@...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>
> Here's a couple candidates:
>
> 8,675,309 (and 8,675,311 - twin primes)
> 1,000,003
> 10^700+7
> 10^999+7
> 4,001
>
> Nathan
>
• 123571113171923 231917131175321 and 23 ones (11111111111111111111111) Ali Adams
Message 3 of 16 , Aug 31, 2009
123571113171923
231917131175321
and 23 ones (11111111111111111111111)

<prime numbers are God's signature>

________________________________
Sent: Monday, August 31, 2009 3:59:44 PM
Subject: [PrimeNumbers] Re: Easily memorized primes

2221!11+1
--- In primenumbers@ yahoogroups. com, Nathan Russell <windrunner@ ...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>
> Here's a couple candidates:
>
> 8,675,309 (and 8,675,311 - twin primes)
> 1,000,003
> 10^700+7
> 10^999+7
> 4,001
>
> Nathan
>

[Non-text portions of this message have been removed]
• 21242!12-1 (digits:6894)
Message 4 of 16 , Aug 31, 2009
21242!12-1 (digits:6894)
--- In primenumbers@yahoogroups.com, Nathan Russell <windrunner@...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>
> Here's a couple candidates:
>
> 8,675,309 (and 8,675,311 - twin primes)
> 1,000,003
> 10^700+7
> 10^999+7
> 4,001
>
> Nathan
>
• ... Lest we forget the entirely under appreciated prime 431: It s the only three digit prime to have descending digits and at the same time yield decreasing
Message 5 of 16 , Aug 31, 2009
--- In primenumbers@yahoogroups.com, Nathan Russell <windrunner@...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>
> Here's a couple candidates:
>
> 8,675,309 (and 8,675,311 - twin primes)
> 1,000,003
> 10^700+7
> 10^999+7
> 4,001
>
> Nathan
>

Lest we forget the entirely under appreciated prime 431: It's the only three digit prime to have descending digits and at the same time yield decreasing digit two digit numbers which are all prime: 43, 41 and 31.

In terms of producing a large prime, it might do that as well:

0^0 + 1^1 + 2^2 + 3^3 + 4^4 + ... + 431^431 is a probable prime. :)

Mark
• ... For the latent numerologist in all of us, we have the ever appealing prime 7^(7*7) + 10^(10*10). And if we want to keep things as simple as 2-3 we have the
Message 6 of 16 , Sep 1, 2009
--- In primenumbers@yahoogroups.com, Nathan Russell <windrunner@...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>

For the latent numerologist in all of us, we have the ever appealing prime

7^(7*7) + 10^(10*10).

And if we want to keep things as simple as 2-3 we have the ever dazzling 2*3 = 6 primes:

2^2^2 + 3^2^2
2^2^2 + 3^2^3
2^2^2 + 3^3^2
2^2^2 + 3^3^3
2^2^3 + 3^2^2
2^3^2 + 3^2^2

Mark
• ... I think it is a bit sad that 11092001 is a prime. As a UK date it tells a story.
Message 7 of 16 , Sep 1, 2009
--- In primenumbers@yahoogroups.com, Nathan Russell <windrunner@...> wrote:
>
> This is more or less a "fun" thread. However, it can occasionally be
> handy to give a concrete example of a large prime to friends, etc.
> None of these are particularly large, but they are easier to memorize
> (for whatever reason) than most primes in their size range.
>
> Here's a couple candidates:
>
> 8,675,309 (and 8,675,311 - twin primes)
> 1,000,003
> 10^700+7
> 10^999+7
> 4,001
>
> Nathan
>

I think it is a bit sad that 11092001 is a prime. As a UK date it tells a story.
• ... 20032003 is a composite number that is hard for me to forget: http://tech.groups.yahoo.com/group/primenumbers/message/11863 David
Message 8 of 16 , Sep 2, 2009
"robert44444uk" <robert_smith44@...> wrote:

> I think it is a bit sad that 11092001 is a prime.
> As a UK date it tells a story.

20032003 is a composite number that is hard for me to forget:

David
Message 9 of 16 , Sep 2, 2009
911 :)

________________________________
Sent: Wednesday, September 2, 2009 5:35:20 PM
Subject: [PrimeNumbers] Re: Easily memorized primes

"robert44444uk" <robert_smith44@ ...> wrote:

> I think it is a bit sad that 11092001 is a prime.
> As a UK date it tells a story.

20032003 is a composite number that is hard for me to forget:

David

[Non-text portions of this message have been removed]
• Hi , all , There may be several different challenges here . ... This is more of an expression than a numeral . ... Yes , but it fails to comply with ISO 8601 ,
Message 10 of 16 , Sep 2, 2009
Hi , all ,

There may be several different challenges here .

> 10^700+7
This is more of an expression than a numeral .

> 11092001 is a prime. As a UK date it tells a story.
Yes , but it fails to comply with ISO 8601 , and is hence
obsolete and confusing , just as e-mail dates often are .

I tend to think of this challenge :
One may be called upon to name a large prime at a social
gathering , prototypically a "cocktail party" .
You may know a large prime , but can you say it ?
A long string of digits can be hard to speak and even
harder to understand , so there is a long-standing and
useful protocol :
911 can be spoken "nine hundred eleven"
( tho nine hundred onety-one would make more sense ) .
When I write below "123" , I mean
"one hundred twenty-three" .
123123456456911 is prime and can be said :
123 trillion 123 billion 456 million 456 thousand 911 .
123123456456789789911 is prime and can be said :
456 trillion 456 billion 789 million 789 thousand 911 .

Cheers ,

Walter
http://upforthecount.com
• ... ............... eleven sextillion one hundred and eleven quintillion one hundred and eleven quadrillion one hundred and eleven trillion one hundred and
Message 11 of 16 , Sep 2, 2009
"Walter Nissen" <nissen@...> wrote:

> You may know a large prime, but can you say it?

..............."eleven sextillion
one hundred and eleven quintillion
one hundred and eleven trillion
one hundred and eleven billion
one hundred and eleven million
one hundred and eleven thousand
one hundred and eleven"

can be said without inhaling

David
• http://primes.utm.edu/curios/page.php?number_id=811 http://primes.utm.edu/curios/page.php?number_id=846 http://primes.utm.edu/curios/page.php?number_id=629 And
Message 12 of 16 , Sep 2, 2009
• ... David stopped at sex and left us almost breathless. But he knows we can have more, much more, with a lot of air to spare. 9 * 10^201 + 1 is prime,
Message 13 of 16 , Sep 2, 2009
>
> "Walter Nissen" <nissen@> wrote:
>
> > You may know a large prime, but can you say it?
>
> ..............."eleven sextillion
> one hundred and eleven quintillion
> one hundred and eleven quadrillion
> one hundred and eleven trillion
> one hundred and eleven billion
> one hundred and eleven million
> one hundred and eleven thousand
> one hundred and eleven"
>
> can be said without inhaling
>
> David
>

David stopped at sex and left us almost breathless. But he knows we can have more, much more, with a lot of air to spare.

9 * 10^201 + 1 is prime, otherwise known as the memorable

Nine Sexsexagintillion and One.

If anyone thinks this sounds like

"Sex, sex again 'till yin and one"

you're imagining things. Get back to work!

Mark
• Suppose that we parse the string cab , in base p, as 12*p^2 + 10*p + 11. Then cab is a prime in the prime base p = 41, where it evaluates to the decimal
Message 14 of 16 , Sep 3, 2009
Suppose that we parse the string "cab", in base p, as
12*p^2 + 10*p + 11. Then "cab" is a prime in the prime
base p = 41, where it evaluates to the decimal number 20593.

Similarly, we may parse the incantation "abracadabra",
in base p, as 10*p^10 + 11*p^9 + 27*p^8 + 10*p^7 + 12*p^6 + 10*p^5
+ 13*p^4 + 10*p^3 + 11*p^2 + 27*p + 10, which evaluates to the prime
8510432846378191 in the prime base p = 31.

The nonce-word "floccinaucinihilipilification" evaluates to the prime
352402927208050896786973658273234894386040810340804173543364510421
in the prime base 199. For the meaning, see
http://www.worldwidewords.org/weirdwords/ww-flo2.htm

Puzzle: Find the smallest prime base in which Aristophanes' dish
http://tinyurl.com/6xkeen
is prime, if we use O'Neill's tranliteration in line 1170 of
http://tinyurl.com/nnaqlk

David
• ... Spoiler space follows. . .. . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . Sum in base 41843 is
Message 15 of 16 , Sep 3, 2009
On 09/03/2009 02:40 AM, djbroadhurst wrote:
> Suppose that we parse the string "cab", in base p, as
> 12*p^2 + 10*p + 11. Then "cab" is a prime in the prime
> base p = 41, where it evaluates to the decimal number 20593.
>
> Similarly, we may parse the incantation "abracadabra",
> in base p, as 10*p^10 + 11*p^9 + 27*p^8 + 10*p^7 + 12*p^6 + 10*p^5
> + 13*p^4 + 10*p^3 + 11*p^2 + 27*p + 10, which evaluates to the prime
> 8510432846378191 in the prime base p = 31.
>
> The nonce-word "floccinaucinihilipilification" evaluates to the prime
> 352402927208050896786973658273234894386040810340804173543364510421
> in the prime base 199. For the meaning, see
> http://www.worldwidewords.org/weirdwords/ww-flo2.htm
>
> Puzzle: Find the smallest prime base in which Aristophanes' dish
> http://tinyurl.com/6xkeen
> is prime, if we use O'Neill's tranliteration in line 1170 of
> http://tinyurl.com/nnaqlk

Spoiler space follows.
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Sum in base 41843 is
9355934623362561735213219302693410823607868190849630269877\
6553684917032146922567250080317347155330911049352272600264891303788077990113278\
4853088920553317989172187911135472248955574815213603926445985233885389642117781\
4381160736048159727697869729116763488380008580384563935286216104489332003841643\
4760106323998198183345546437753307049885244185702893171182361757187414650365639\
1793563743445464735466507739792305201194704747538514165228148227347542716827410\
3317461237255320643879853668183786679561917227974652256331446555994563730135516\
3026904731364993396280828241651057013994638897984779596310112725585193309862898\
9978162623129572344332751322965737425155187359894442966740804307156470888035472\
2453994844494330604029034206329792396426299163600028180427618021437461076507541\
3062782241110381733982885164991797153719562713304314423

--
Alan Eliasen
eliasen@...
http://futureboy.us/
• ... gave a solution in agreement with [spoiler!] http://primes.utm.edu/curios/page.php?number_id=9432 More ambitiously, one might consider the 1185-letter word
Message 16 of 16 , Sep 3, 2009
--- In primenumbers@yahoogroups.com, Alan Eliasen <eliasen@...>
gave a solution in agreement with [spoiler!]
http://primes.utm.edu/curios/page.php?number_id=9432

More ambitiously, one might consider the 1185-letter word
for the Tobacco Mosaic Virus, Dahlemense Strain, at
http://www.fun-with-words.com/word_longest.html

By my reckoning, this is probably prime in
20 different prime bases less than 10^6.

David
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