Happy 11/11/11 !

[science_man_88]

Originally Posted by Flatlander

What about Captain Slog and his stardate?

I remember contemplating 7/7/77 and one of Fergie's daughters was born 8/8/88 at 8:18 iirc.

well using the fact that all the digits are equal regardless makes it slightly less rare x/y/z where x=y=z happens 12 times but by pari script I got:

1/1/1
1/1/11
1/11/1
1/11/11
2/2/2
2/2/22
2/22/2
2/22/22
3/3/3
3/3/33
4/4/4
4/4/44
5/5/5
5/5/55
6/6/6
6/6/66
7/7/7
7/7/77
8/8/8
8/8/88
9/9/9
9/9/99
10/10/10
11/1/1
11/1/11
11/11/1
11/11/11
12/12/12

if the digits can just be equal within them. over twice as common, almost 3 times.

[Mathew]

Warning: A 4-letter word is used twice the word is synonymous with

[stathmk]

Originally Posted by ckdo

Happy Skyrim day, everyone!

I’m not quite sure what you mean, but I have an email friend who plays The Elder Scrolls 4: Oblivion. I thought that I’d tell you that I found this Skyrim file on Fileplanet.com today: http://www.fileplanet.com/223223/220000/fileinfo/Elder-Scrolls-V:-Skyrim-%27Making-A-Dragon-Sandwich-|-The-Sound-of-Skyrim%27-Trailer

I want to check out the book “The Eleventh Hour: A Curious Mystery by Graeme Base” from the library to read it to my niece. It’s a mystery and poem with talking animals about a stolen birthday feast on the 11th afternoon hour of the 11th day of the 11th month of the year on somebody’s 11th birthday. It’s written by the same author as Animalia and I kind-of think that he’s won a Caldecott award for illustration. I haven’t read it since I was with an elementary school friend about 20 years ago.

I’ve played The 11th Hour computer game. If you don’t like The 7th Guest, then you won’t like The 11th Hour. If you do like the The 7th Guest, then you’ll like the 11th Hour. It’s all puzzles. I have the strategy guides for both games. I can beat The 7th Guest. I can only make it to the attic puzzle in The 11th Hour and it won’t let me click on anything there for some reason.

Edit: November 11th is also Veteran's Day in America

[stathmk]

Originally Posted by gd_barnes

No, although if you truncate some digits, you get 4 primes:

11 = prime
111 = 3 * 37
1111 = 11 * 101
11111 = 41 * 271
111111 = 3 * 7 * 11 * 13 * 37
1111111 = 239 * 4649
11111111 = 11 * 73 * 101 * 137
111111111 = 3^2 * 37 * 333667
1111111111 = 11 * 41 * 271 * 9091
11111111111 = 21649 * 513239
111111111111 = 3 * 7 * 11 * 13 * 37 * 101 * 9901
2 = prime
20 = 2^2 * 5
201 = 3 * 67
2011 = prime
20111 = 7 * 13^2 * 17
201111 = 3 * 43 * 1559
2011111 = prime
20111111 = 643 * 31277
201111111 = 3^2 * 149 * 149971
2011111111 = 29 * 59 * 919 * 1279
20111111111 = 7^3 * 13 * 4510229
201111111111 = 3 * 229 * 292738153
2011111111111 = 24223 * 83024857
20111111111111 = 281 * 1283 * 55783157

You have the year 2011 concatenated with a long string of ones. It reminds me that I discovered with Primeform that 2007*10^15821+(10^15821-1)/9 is a 15,825-digit probable prime written as 200711111…11111. I submitted it to http://www.primenumbers.net/prptop/prptop.php in November 2009.

[Batalov]

2011 is prime
2011111 is prime
(181*10^20-1)/9 is prime
(181*10^29-1)/9 is prime
(181*10^95-1)/9 is prime
(181*10^168-1)/9 is prime
(181*10^1836-1)/9 is 3-PRP!
(181*10^2693-1)/9 is 3-PRP!
(181*10^2922-1)/9 is 3-PRP!
(181*10^11364-1)/9
(181*10^13775-1)/9
(181*10^17138-1)/9 *
and many more fractions of the 11th second of the 11th minute...

[gd_barnes]

I guess I should have considered the 4-digit year at the end and in the middle as in 11:11:11 11-11-2011 or 11-11-2011 11:11:11. Using those combinations, we have quite a few decent primes, i.e.

[2011 at the end; 1 thru 4 digits already shown]
12011 = prime
112011 = 3 * 37337
1112011 = prime
11112011 = prime
111112011 = 3^2 * 23 * 536773
1111112011 = 61 * 79 * 97 * 2377
11111112011 = 19 * 757 * 772517
111111112011 = 3 * 47 * 788022071
1111111112011 = 59 * 97397 * 193357
11111111112011 = 53 * 141991 * 1476457

[2011 in the middle:
From the right; 1 thru 10 digits already shown.
From the left; 1 thru 4, 8, and 14 digits already shown.]
From the right:
12011111111 = prime
112011111111 = 3 * 56783 * 657539
1112011111111 = prime
11112011111111 = 101 * 263 * 18199 * 23003
From the left:
11112 = 2^3 * 3 * 463
111120 = 2^4 * 3 * 5 * 463
1111201 = 7 * 13 * 12211
111120111 = 3^2 * 12346679
1111201111 = 19 * 58484269
11112011111 = 53 * 209660587
111120111111 = 3 * 2521 * 14692597
1111201111111 = 7 * 13 * 12211001221

So we have a total of 9 primes from all combinations of digits, the longest of which is 13 digits:
2
11
2011
12011
1112011
2011111
11112011
12011111111
1112011111111

Not a bad haul for only 14 digits.

[Batalov]

...and (181*10^40284-1)/9

[stathmk]

11/11/11 reminds me that these are the repunit primes:
(10^0-1)/9 (0 and technically not prime)
(10^1-1)/9 (1 digit and technically not prime)
(10^2-1)/9 (2 digits)
(10^19-1)/9 (19 digits)
(10^23-1)/9 (23 digits)
(10^317-1)/9 (317 digits)
(10^1031-1)/9 (1,031 digits and discovered in Dec 1985 at http://primes.utm.edu/top20/page.php?id=57 )
Repunit probable primes and a probable prime factor from http://www.primenumbers.net/prptop/searchform.php?form=%2810^x-1%29%2F%3F&action=Search :
(10^49081-1)/9 (49,081 digits and discovered in Sept 1999)
(10^76537-1) isn’t a probable prime, however (10^76537-1)/(9*66,127,969) is a 76,529-digit probable prime discovered in April 2009
(10^86453-1)/9 (86,453 digits and discovered in Oct 2000)
(10^109297-1)/9 (109,297 digits and discovered in April 2007)
(10^270343-1)/9 (270,343 digits and discovered in Sept 2007)
(10^524287-1)/9 is NOT a probable prime and it took me 2 weeks of using Primeform in 2007 to show that it isn’t.

Please post which repunits, if any, you have tested. If each person just spent time testing only one number above 270,343 digits then I would be grateful. Maybe eventually, somebody will find another repunit probable prime! Is anybody besides me interested in contributing to a project of people reserving different repunits and trying to prove them as probable primes? I want to spend a couple weeks of computer time myself every year on this so that the project doesn’t look dead.

[stathmk]

I found out about an hour ago about repunit.org. It’s a more appropriate project to join than the repunit project that I was planning on starting.

[Oddball]

This news release has a date and time of 2011-11-11 11:11:
http://www.top500.org/lists/2011/11/press-release

[science_man_88]

Originally Posted by Oddball

This news release has a date and time of 2011-11-11 11:11:
http://www.top500.org/lists/2011/11/press-release

it does not utilize graphics processors or other accelerators. what would it do if it did my guess is melt but if they upgrade to GPU it might go into the exaflop range soon enough.