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Old 2018-01-16, 23:48   #1
hydeer
 
Jan 2018

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Default Highest Prime is also a twin prime... NOT

By coincidence, the largest known prime is also a twin prime, that is 2 larger.
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Old 2018-01-16, 23:57   #2
ATH
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No, it is not a twin prime. 277232917+1 is divisible by 3, and 277232917-3 is not prime:

Quote:
2^77232917-3 is not prime. RES64: 6F0CC152285F2E9F. Wg8: F9C5D09F,00000000

You are welcome to run a double check of 277232917-3 or search for a factor of it above 1.22*1013. The worktodo.txt for Prime95/mprime is:
PRP=1,2,77232917,-3

It will take 2-14 days depending on your CPU speed.

Last fiddled with by ATH on 2018-01-17 at 00:00
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Old 2018-01-18, 10:34   #3
LaurV
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Quote:
Originally Posted by ATH View Post
No, it is not a twin prime. <snip> The worktodo.txt for Prime95/mprime is:
PRP=1,2,77232917,-3
It will take 2-14 days depending on your CPU speed.
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Old 2018-01-28, 21:26   #4
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Is there a place to report on such values?

Code:
UID: manoli94/Oliver-PC, 2^77232917-3 completed P-1, B1=5000000, B2=500000000, E=12, Wg4: D0001B57
By the way... Title of this thread and first post don't really match. (I guess everyone saw that already, I might be a bit slow on that)
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Old 2018-04-02, 18:20   #5
hydeer
 
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Default 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.
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Old 2018-04-02, 18:29   #6
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Quote:
Originally Posted by hydeer View Post
One less than a primorial is always prime number
No it is not 2*3*5*7=210; 209=11*19

Last fiddled with by science_man_88 on 2018-04-02 at 18:29
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Old 2018-04-02, 18:36   #7
Dubslow
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2*3*5*7*11*13*17 - 1 = 61 * 8369
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Old 2018-04-03, 09:10   #8
retina
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Quote:
Originally Posted by hydeer View Post
One less than a primorial is always prime number.
Is this a new definition of "prime number" that we were previously unaware of?
Quote:
A prime number is any number that is one less than a primorial.
Seems legit to me.
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Old 2018-04-03, 13:58   #9
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I ran a simple-minded 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]
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Old 2018-04-03, 22:54   #10
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Quote:
Originally Posted by retina View Post
Is this a new definition of "prime number" that we were previously unaware of?Seems legit to me.
Nope! It's just a new definition of the word "always".

Literally, it means "sometimes but not often"
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