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Old 2019-06-10, 13:07   #100
sweety439
 
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Since all Sierp bases <= 1030 have a k=7 prime, thus I try to find the smallest Sierp base without known prime for k=7 and continue searched Sierp k=7 for larger bases (b>1030) and find such Sierp bases would be 1136....

Only list even bases, since for odd bases all the k=7 numbers are divisible by 2.
Attached Files
File Type: txt Sierp k=7 for bases gt 1004.txt (541 Bytes, 52 views)

Last fiddled with by sweety439 on 2019-06-10 at 13:08
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Old 2019-06-14, 23:06   #101
gd_barnes
 
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Files in post #62 updated again.
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Old 2019-06-17, 10:32   #102
henryzz
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Code:
Riesel k=13:
b==(1 mod 2) has a factor of 2
b==(1 mod 3) has a factor of 3
b==(20 mod 21) has a covering set of [3, 7]
b==(38 or 302 mod 510) have a covering set of [3, 5, 17]
  (This includes bases 38, 302, 548, 812.)
Proth k=13:
b==(1 mod 2) has a factor of 2
b==(1 mod 7) has a factor of 7
b==(20 mod 21) has a covering set of [3, 7]
b==(132 and 888) have a covering set of [5, 7, 17] // probably mod 1190
remaining at 25k:
Code:
13*422^n-1 - searched to 200k
13*446^n-1 - searched to 300k
13*542^n-1 - prime at 70447
13*698^n-1 - searched to 150k
13*842^n-1 - searched to 100k
13*962^n-1 - searched to 100k

13*244^n+1
13*326^n+1 - prime at 56864
13*338^n+1 - prime at 37612
13*422^n+1 - searched to 200k
13*458^n+1 - prime at 306196
13*536^n+1 - searched to 300k
13*542^n+1 - searched to 200k
13*560^n+1
13*620^n+1 - searched to 200k
13*656^n+1 - searched to 100k
13*668^n+1
13*720^n+1 - searched to 400k
13*740^n+1 - searched to 200k
13*748^n+1 - prime at 32635
13*758^n+1
13*808^n+1 - searched to 100k
13*842^n+1 - searched to 400k
13*872^n+1 - prime at 38782
13*878^n+1 - searched to 150k
13*920^n+1 - searched to 300k
13*926^n+1 - searched to 100k
13*958^n+1 - prime at 101751
13*992^n+1 - searched to 100k
I will sieve and search the 4 sierpinski bases only searched to 25k(244, 560, 668, 758)
Attached Files
File Type: zip rieselk13.zip (1.6 KB, 37 views)
File Type: zip prothk13.zip (1.9 KB, 40 views)
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Old 2019-08-29, 13:25   #103
LaurV
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Here it was. Link back.
With the current found.

Last fiddled with by LaurV on 2019-08-29 at 13:27
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Old 2019-12-10, 02:43   #104
gd_barnes
 
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I have searched all remaining k=2 thru 12 for bases <= 1030 to n=100K.

There were 42 k/base combos that had previously only been searched to n=25K. Here are the combos that were searched for n=25K-100K:
Riesel:
k=4 b=303
k=4 b=921
k=6 b=768
k=8 b=283
k=8 b=374
k=8 b=432
k=8 b=721
k=8 b=728
k=9 b=566
k=9 b=570
k=10 b=284
k=10 b=899
k=11 b=804
k=12 b=263

Sierp:
k=2 b=801
k=5 b=824
k=6 b=509
k=6 b=522
k=8 b=254
k=8 b=389
k=8 b=434
k=8 b=575
k=8 b=824
k=8 b=1014
k=9 b=884
k=10 b=432
k=10 b=614
k=10 b=668
k=10 b=786
k=10 b=863
k=10 b=986
k=11 b=560
k=12 b=230
k=12 b=359
k=12 b=362
k=12 b=481
k=12 b=593
k=12 b=692
k=12 b=700
k=12 b=923
k=12 b=1019
k=12 b=1022

Primes found:
4*921^98667-1
6*768^70213-1
6*522^52603+1
8*254^67715+1
10*786^68168+1
10*986^48278+1
12*230^94750+1
12*359^61294+1
12*481^45940+1
12*593^42778+1
12*700^91952+1
12*923^64364+1

All k<=12 for b<=1030 have now been searched to n>=100K. :-)

The web pages and the files in post 62 in this thread have been updated accordingly.

Last fiddled with by gd_barnes on 2019-12-10 at 02:46
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Old 2020-02-18, 07:17   #105
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I've found:
8*283^164768-1 is prime

Base 283 for k=8 tested to n=166k.
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Old 2020-05-05, 07:14   #106
kar_bon
 
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8*97^192335-1 is prime (382127 digits)
8*97^n-1 tested for 100000<n<200000
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Old 2020-05-25, 11:30   #107
kar_bon
 
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4*303^198357-1 is prime, 492,213 digits
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Old 2020-05-25, 20:55   #108
gd_barnes
 
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The web pages and the files in post 62 in this thread have been updated for the recent finds.
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Old 2020-08-03, 06:28   #109
kar_bon
 
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4*438^n-1 is tested through n=300k, no prime.
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