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 2013-03-10, 23:08 #1 ishkibibble   Nov 2012 Canada 3·7 Posts Prime testing software suggestions please. I'm trying to determine if (30^78857-1)/29 is prime. Three types of software I used have crashed testing this. Thank you for any pointers.
 2013-03-10, 23:17 #2 firejuggler     "Vincent" Apr 2010 Over the rainbow 22·7·103 Posts you want to look for pfgw. (30^78857-1)/29 is 3-PRP! (51.9943s+0.0034s) so, most probably prime. Last fiddled with by firejuggler on 2013-03-10 at 23:19
2013-03-11, 00:24   #3
henryzz
Just call me Henry

"David"
Sep 2007
Liverpool (GMT/BST)

37×163 Posts

Quote:
 Originally Posted by ishkibibble I'm trying to determine if (30^78857-1)/29 is prime. Three types of software I used have crashed testing this. Thank you for any pointers.
(30^78857-1)/29 -1 = 30*(30^78856-1)/29

(30^78856-1) has algebraic factors since 78856 isn't prime.
You might be able to use this to make a primality prove with a N-1 test.
You would need to factor I think 33% of N-1 and then put them in a helper file for PFGW.

 2013-03-11, 00:44 #4 firejuggler     "Vincent" Apr 2010 Over the rainbow B4416 Posts henryzz i'm afraid you made a mistake there... 30*(30^78856-1)/29 is composite: RES64: [D3B186476037718B] (304.1575s+0.0032s) maybe you meant ((30*30^78856)-1)/29?
2013-03-11, 01:24   #5
henryzz
Just call me Henry

"David"
Sep 2007
Liverpool (GMT/BST)

178F16 Posts

Quote:
 Originally Posted by firejuggler henryzz i'm afraid you made a mistake there... 30*(30^78856-1)/29 is composite: RES64: [D3B186476037718B] (304.1575s+0.0032s) maybe you meant ((30*30^78856)-1)/29?
(30^78857-1)/29 -1 = 30*(30^78856-1)/29
Notice the -1.
It is interesting how the lack of special modulus slowed the testing down by a factor of 6.

 2013-03-11, 01:54 #6 firejuggler     "Vincent" Apr 2010 Over the rainbow 22·7·103 Posts my bad.
 2013-03-11, 20:14 #7 ishkibibble   Nov 2012 Canada 3×7 Posts primetest I was able to complete one test where the value is shown as prime. I will test the same value on different software and platforms. PFGW is on the list for benchmarking. ty!
 2013-03-11, 20:34 #8 firejuggler     "Vincent" Apr 2010 Over the rainbow 22×7×103 Posts If you have small prime - below 8000 digits- and want *definite* proof ,there is a program called 'primo' here certification take from a few second for a 300 digits prime to a few day for a 8000 digits prime Last fiddled with by firejuggler on 2013-03-11 at 20:36
2013-03-11, 21:58   #9
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

3×7×479 Posts

Quote:
 Originally Posted by ishkibibble I was able to complete one test where the value is shown as prime. I will test the same value on different software and platforms. PFGW is on the list for benchmarking. ty!
And what test would that be?

How far have you factored (30^78856-1)/29 (which will produce helpers for the N-1 test)?

2013-03-11, 22:03   #10
Batalov

"Serge"
Mar 2008
Phi(4,2^7658614+1)/2

3×7×479 Posts

Quote:
 Originally Posted by ishkibibble I'm trying to determine if (30^78857-1)/29 is prime. Three types of software I used have crashed testing this. Thank you for any pointers.
It is a known PRP, found by R.Price.

 2013-03-11, 22:03 #11 firejuggler     "Vincent" Apr 2010 Over the rainbow 22×7×103 Posts here had a free core, ran a few curve/pm1 still a looooooooooooong way before using N-1

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