20050910, 21:30  #1 
"Jason Goatcher"
Mar 2005
3507_{10} Posts 
possibly stupid question about winning the $100,000
Not understanding the proving math, but having a good memory, wouldn't calculating "primorial 1billion minus 1" technically create a record prime?
Or is there some lawyer wording to prevent this? "I'm assuming I'm correct in the assumption that primorial x minus 1 is always prime. Primorial x means multiplying all the primes from 1 to x, correct? Last fiddled with by jasong on 20050910 at 21:30 
20050910, 21:42  #2 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
Step 1 (always!): Look at small cases.
Alex 
20050910, 22:21  #3  
"Jason Goatcher"
Mar 2005
110110110011_{2} Posts 
Quote:


20050910, 22:34  #4 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
>I know it's correct for the first five.
2*3*5*71 = 209 = 11*19 For the primorial n#, n#ยฑ1 has no prime divisor โคn, but can very well have larger divisors. Alex Last fiddled with by akruppa on 20050916 at 14:52 
20050910, 22:40  #5 
Aug 2005
Brazil
2·181 Posts 
Other than that, there is another constraint: Calculating the primorial for 1 billion digit would actually involve knowing every other prime below it.

20050910, 22:55  #6 
"Nancy"
Aug 2002
Alexandria
2,467 Posts 
I read jasong's suggestion as 1000000000#1, i.e.
Computing the primes <10^9 is quite easy, but the product will be pretty large. Alex (my TeXfu is weak . This took way too long) 
20050910, 23:18  #7 
"Jason Goatcher"
Mar 2005
3507_{10} Posts 
Okay, I'm confused, am I right or wrong about the idea that primorial x minus 1 is prime? I seem to remember a proof, but...

20050910, 23:25  #8 
"Mark"
Apr 2003
Between here and the
2^{3}·19·43 Posts 
Check out http://primorialprime.home.comcast.net/. It is a search for primorial primes. You can clearly see that there are few primorials.

20050910, 23:32  #9  
"Jason Goatcher"
Mar 2005
6663_{8} Posts 
Quote:
Okay, this goes in the bin along with the mentally ill delusion I used to have that Saddam Hussein and Bill Clinton were in cahoots. (Cahoots over what? I don't remember) 

20050910, 23:34  #10  
"Jason Goatcher"
Mar 2005
110110110011_{2} Posts 
Quote:
Last fiddled with by jasong on 20050910 at 23:37 

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