20180116, 23:48  #1 
Jan 2018
3_{8} Posts 
Highest Prime is also a twin prime... NOT
By coincidence, the largest known prime is also a twin prime, that is 2 larger.

20180116, 23:57  #2  
Einyen
Dec 2003
Denmark
110101101010_{2} Posts 
No, it is not a twin prime. 2^{77232917}+1 is divisible by 3, and 2^{77232917}3 is not prime:
Quote:
You are welcome to run a double check of 2^{77232917}3 or search for a factor of it above 1.22*10^{13}. The worktodo.txt for Prime95/mprime is: PRP=1,2,77232917,3 It will take 214 days depending on your CPU speed. Last fiddled with by ATH on 20180117 at 00:00 

20180118, 10:34  #3 
Romulan Interpreter
"name field"
Jun 2011
Thailand
10,273 Posts 

20180128, 21:26  #4 
"Oliver"
Sep 2017
Porta Westfalica, DE
527_{16} Posts 
Is there a place to report on such values?
Code:
UID: manoli94/OliverPC, 2^772329173 completed P1, B1=5000000, B2=500000000, E=12, Wg4: D0001B57 
20180402, 18:20  #5 
Jan 2018
3 Posts 
twin primes
One less than a primorial is always prime number. One more than a primorial may be a twin prime. For example, primorial [5] 1= 2 . 3 . 5 = 29 and primorial [5] + 1 = 31. So primorial [ 5 ] has a so called twin two years older.

20180402, 18:29  #6 
"Forget I exist"
Jul 2009
Dartmouth NS
2·3·23·61 Posts 
No it is not 2*3*5*7=210; 209=11*19
Last fiddled with by science_man_88 on 20180402 at 18:29 
20180402, 18:36  #7 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
16065_{8} Posts 
2*3*5*7*11*13*17  1 = 61 * 8369

20180403, 09:10  #8 
Undefined
"The unspeakable one"
Jun 2006
My evil lair
6,679 Posts 

20180403, 13:58  #9 
Feb 2017
Nowhere
2^{2}·1,553 Posts 
I ran a simpleminded Pari script to check whether p# +/ 1 was a pseudoprime for primes p up to 500. After the prime p, a  sign appears if p# 1 is a pseudoprime; a + sign appears if p# + 1 is a pseudoprime. If neither p#  1 nor p# + 1 is a pseudoprime, the word "neither" appears after p.
[2 +, 3  +, 5  +, 7 +, 11  +, 13  , 17 neither, 19 neither, 23 neither, 29 neither, 31 +, 37 neither, 41  , 43 neither, 47 neither, 53 neither, 59 neither, 61 neither, 67 neither, 71 neither, 73 neither, 79 neither, 83 neither, 89  , 97 neither, 101 neither, 103 neither, 107 neither, 109 neither, 113 neither, 127 neither, 131 neither, 137 neither, 139 neither, 149 neither, 151 neither, 157 neither, 163 neither, 167 neither, 173 neither, 179 neither, 181 neither, 191 neither, 193 neither, 197 neither, 199 neither, 211 neither, 223 neither, 227 neither, 229 neither, 233 neither, 239 neither, 241 neither, 251 neither, 257 neither, 263 neither, 269 neither, 271 neither, 277 neither, 281 neither, 283 neither, 293 neither, 307 neither, 311 neither, 313 neither, 317  , 331 neither, 337  , 347 neither, 349 neither, 353 neither, 359 neither, 367 neither, 373 neither, 379 +, 383 neither, 389 neither, 397 neither, 401 neither, 409 neither, 419 neither, 421 neither, 431 neither, 433 neither, 439 neither, 443 neither, 449 neither, 457 neither, 461 neither, 463 neither, 467 neither, 479 neither, 487 neither, 491 neither, 499 neither] 
20180403, 22:54  #10 
Jun 2015
Vallejo, CA/.
10001111010_{2} Posts 

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