20070107, 03:09  #34  
Jun 2003
Oxford, UK
2·7·137 Posts 
Base 16
Quote:
Quote:
Robert Smith 

20070107, 06:57  #35 
Jun 2003
1,579 Posts 
For base 10, 9701 is a smaller riesel number. 10176 is not a riesel number.
and 9175 for sierpinski side. Last fiddled with by Citrix on 20070107 at 07:17 
20070107, 09:07  #36  
Jun 2003
Oxford, UK
2×7×137 Posts 
Base 10
Quote:
Regarding the Riesel, I rechecked my worksheet, and certainly 10176 is a Riesel [7,11,13,37] base 10. The first six values of n factor as: 1 7*14537 2 11*79*1171 3 37*275027 4 11*9250909 5 13*7433*10531 6 11*37*67*373171 Regarding your suggested value 9701, the first six factorise as follows: 1 11*8819 2 13*74623 3 7*11*17*7411 4 907*106957 5 11*5807*15187 6 1811*5356709 I agree there are no primes up to n=2000. What is your covering set? Regards Robert Smith 

20070107, 09:15  #37  
Jun 2003
Oxford, UK
2×7×137 Posts 
Sticky
Quote:
Base Lowest known Sierpinski number Covering set Proven? Y/N # of remaining candidates to be checked Who is checking? Lowest known Riesel number Covering set Proven? Y/N # of remaining candidates to be checked Who is checking? I am no longer a moderator, so I can't create this. Anyone up to spending a useful hour doing this? What do others think? Regards Robert Smith 

20070107, 10:02  #38  
Jun 2003
Oxford, UK
1918_{10} Posts 
Masser, is this you?
Quote:
The base 3 values, and their discoverers, after doing a bit of research, are: Sierpinski 3574321403229074 [5,7,13,17,41,73,97,193,769,6481] (Jack Brennan yahoo primenumbers 2002) Riesel 739171331147778631 [5,7,13,17,19,37,73,97,577,757,769] (Tom Masser 2004) http://tech.groups.yahoo.com/group/p...m/message/4690 Masser, are you one and the same person? Given that the Riesel is more than 10^2 larger, there is a chance this is not the lowest. Actually neither are proven!! Regards Robert 

20070107, 10:46  #39 
Jun 2003
Oxford, UK
2·7·137 Posts 
Base 21
Here is a nice easy one:
Base 21, covering set [11,13,17] repeating every 4 n Sierpinski candidate 1002, checked all smaller non trivial, only one remaining k=118 checked to n=3500 Riesel candidate 560, checked all smaller non trivial, proven, last candidate was k=64 but prime 64*21^28671 
20070107, 11:40  #40  
Oct 2006
100000011_{2} Posts 
1468*11^26258+1 is a probable prime. Time: 201.897 sec.
i don't know how to verify that it is really prime or not i will take the 2 last sierpinski base 11 to finish it. Quote:
Last fiddled with by tnerual on 20070107 at 11:54 

20070107, 12:54  #41 
Jun 2003
Oxford, UK
2×7×137 Posts 
Base 22
Base 22 is a bit more exciting:
Sierpinski 6694 [5,23,97], 15 candidates left at n=2000, actually 22 and 484 are out of the same house, so really there are only 14. 22,346,484,942,1611,1726,1908,2991,4233,5061,5128,5659,5751,6234,6462 Riesel 4461 [5,23,97] also 14 candidates left at n=2000 185,1013,1119,1335,2529,2853,3104,3426,3656,4001,4070,4118,4302,4440 I found a relatively efficient way to check to see if any of the candidates is a possible undiscovered candidate. Just run all of the numbers in a pfgw batch with the f100 flag, over a range of 120n and pfgw will try to factorise it. Cut and paste the results into a sorter and look at the results for each candidate. I did this with the base 22 results, and therefore know that the remaining candidates are non sierpinski or riesel. I left 19 out because it is a bit complex, and need time to look at the possible combinations. Well done, tneural, quite a big find!! 
20070107, 17:59  #42 
Jan 2005
737_{8} Posts 
Make that three down:
346*22^3180+1 is prime 1726*22^2120+1 is prime 1119*22^28491 is prime Last fiddled with by michaf on 20070107 at 18:53 Reason: 3 down 
20070107, 18:33  #43  
Oct 2006
7×37 Posts 
Quote:
if it is i'm lucky/stupid (confusion between 1 and +1 with 416 one of the two last k in sierpinski side) LAurent 

20070107, 19:05  #44 
Jan 2005
737_{8} Posts 
Without any math skills... so excuse me if I bugger here :>
base 22: 22*22^n + 1 = 22^(n+1) + 1 = 1*22^(n+1) + 1 so, k = 1 and that one is eliminated, therefore is k=22 and 484? 
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