mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > Math

Reply
 
Thread Tools
Old 2005-07-25, 16:46   #12
alpertron
 
alpertron's Avatar
 
Aug 2002
Buenos Aires, Argentina

22×3×53 Posts
Default

By the way, I wrote a program in UBASIC to compute the lowest value of Q for which both n#+Q and n#-Q are Fermat pseudoprimes base 3:

Code:
  n       Q
 11 	 23 
 13 	 17 
 17 	 59 
 19 	 23 
 23 	 79 
 29 	 101 
 31 	 83 
 37 	 239 
 41 	 71 
 43 	 149 
 47 	 367 
 53 	 73 
 59 	 911 
 61 	 313 
 67 	 373 
 71 	 523 
 73 	 313 
 79 	 331 
 83 	 197 
 89 	 101 
 97 	 1493 
 101 	 523 
 103 	 293 
 107 	 577 
 109 	 2699 
 113 	 1481 
 127 	 1453 
 131 	 5647 
 137 	 647 
 139 	 419 
 149 	 757 
 151 	 4253 
 157 	 509 
 163 	 239 
 167 	 10499 
 173 	 191 
 179 	 4013 
 181 	 2659 
 191 	 617 
 193 	 6733 
 197 	 1297 
 199 	 971 
 211 	 10093 
 223 	 313 
 227 	 1871 
 229 	 883 
 233 	 443 
 239 	 1009 
 241 	 1471 
 251 	 12689 
 257 	 2861 
 263 	 8231 
 269 	 7127 
 271 	 1217 
 277 	 5471 
 281 	 7673 
 283 	 773 
 293 	 10987 
 307 	 3643 
 311 	 331 
 313 	 3533 
 317 	 8111 
 331 	 6427 
 337 	 2441 
 347 	 1627 
 349 	 9829 
 353 	 937 
 359 	 4973 
 367 	 373 
 373 	 10501 
 379 	 1327 
 383 	 2711 
 389 	 16481 
 397 	 14717 
 401 	 8093 
 409 	 26777 
 419 	 31271 
 421 	 677 
 431 	 31957 
 433 	 2503 
 439 	 42829 
 443 	 5519 
 449 	 57089 
 457 	 6491 
 461 	 1021 
 463 	 27919 
 467 	 941 
 479 	 22441 
 487 	 54091 
 491 	 10987 
 499 	 691 
 503 	 17669 
 509 	 27527 
 521 	 20731 
 523 	 4001 
 541 	 18859 
 547 	 3457 
 557 	 13337 
 563 	 75391 
 569 	 25237 
 571 	 29077 
 577 	 11593 
 587 	 11483 
 593 	 10691 
 599 	 11777 
 601 	 21149 
 607 	 162527 
 613 	 66403 
 617 	 31991 
 619 	 60889 
 631 	 5179
Notice that in no case is Q >= n2, so all these values of Q are prime numbers.
alpertron is offline   Reply With Quote
Old 2005-07-25, 18:10   #13
AntonVrba
 
AntonVrba's Avatar
 
Jun 2005

2·72 Posts
Default

Quote:
Originally Posted by alpertron
By the way, I wrote a program in UBASIC to compute the lowest value of Q for which both n#+Q and n#-Q are Fermat pseudoprimes base 3:

Code:
  n       Q
 11 	 23 
 13 	 17 
 17 	 59 
 etc
Notice that in no case is Q >= n2, so all these values of Q are prime numbers.
Yes indeed they are all prime provable by other software (in my case mathematica or PFGW), demonstrating Conjecture 5 as True.

If Conjecture 5 can be prooven then a new algorithm for prooving numbers prime can be developped that will shorten the computing time

Last fiddled with by AntonVrba on 2005-07-25 at 18:17
AntonVrba is offline   Reply With Quote
Old 2005-07-25, 20:35   #14
flava
 
flava's Avatar
 
Feb 2003

11101102 Posts
Default

I don't know if it's of any interest, but here are some quick results for lowest Q for p(i)#+-Q both prime. All Q here are prime.

Code:
p(10)# + 101
p(10)# - 101

p(11)# + 83
p(11)# - 83

p(12)# + 239
p(12)# - 239

p(13)# + 71
p(13)# - 71

p(14)# + 149
p(14)# - 149

p(15)# + 367
p(15)# - 367

p(16)# + 73
p(16)# - 73

p(17)# + 911
p(17)# - 911

p(18)# + 313
p(18)# - 313

p(19)# + 373
p(19)# - 373

p(20)# + 523
p(20)# - 523

p(21)# + 313
p(21)# - 313

p(22)# + 331
p(22)# - 331

p(23)# + 197
p(23)# - 197

p(24)# + 101
p(24)# - 101

p(25)# + 1493
p(25)# - 1493

p(26)# + 523
p(26)# - 523

p(27)# + 293
p(27)# - 293

p(28)# + 577
p(28)# - 577

p(29)# + 2699
p(29)# - 2699

p(30)# +1481
p(30)# -1481

p(31)# + 1453
p(31)# - 1453

p(32)# + 5647
p(32)# - 5647

p(33)# + 647
p(33)# - 647

p(34)# + 419
p(34)# - 419

p(35)# + 757
p(35)# - 757

p(36)# + 4253
p(36)# - 4253

p(37)# + 509
p(37)# - 509

p(38)# + 239
p(38)# - 239

p(39)# + 10499
p(39)# - 10499

p(40)# + 191
p(40)# - 191

p(41)# + 4013
p(41)# - 4013

p(42)# + 2659
p(42)# - 2659

p(43)# + 617
p(43)# - 617

p(44)# + 6733
p(44)# - 6733

p(45)# + 1297
p(45)# - 1297

p(46)# + 971
p(46)# - 971

p(47)# + 10093
p(47)# - 10093

p(48)# + 313
p(48)# - 313

p(49)# + 1871
p(49)# - 1871

p(50)#+883
p(50)#-883


p(100)# + 18859
p(100)# - 18859

p(101)# + 3457
p(101)# - 3457

p(200)# + 99259
p(200)# - 99259

p(201)# + 90677
p(201)# - 90677
flava is offline   Reply With Quote
Old 2005-07-25, 22:07   #15
alpertron
 
alpertron's Avatar
 
Aug 2002
Buenos Aires, Argentina

22·3·53 Posts
Default

To satisfy my curiosity I extended the table up to 1000:

Code:
 n      Q        ln(Q)/ln(ln(n#))
 5      7            1.590
 7      13           1.530
 11     23           1.532
 13     17           1.214
 17     59           1.583
 19     23           1.129
 23     79           1.478
 29     101          1.480
 31     83           1.356
 37     239          1.616
 41     71           1.215
 43     149          1.385
 47     367          1.591
 53     73           1.128
 59     911          1.751
 61     313          1.446
 67     373          1.463
 71     523          1.519
 73     313          1.372
 79     331          1.365
 83     197          1.225
 89     101          1.056
 97     1493         1.651
 101    523          1.397
 103    293          1.253
 107    577          1.388
 109    2699         1.707
 113    1481         1.562
 127    1453         1.543
 131    5647         1.815
 137    647          1.348
 139    419          1.247
 149    757          1.358
 151    4253         1.699
 157    509          1.258
 163    239          1.098
 167    10499        1.843
 173    191          1.039
 179    4013         1.630
 181    2659         1.540
 191    617          1.247
 193    6733         1.701
 197    1297         1.376
 199    971          1.313
 211    10093        1.750
 223    313          1.085
 227    1871         1.416
 229    883          1.268
 233    443          1.134
 239    1009         1.281
 241    1471         1.345
 251    12689        1.735
 257    2861         1.455
 263    8231         1.641
 269    7127         1.608
 271    1217         1.283
 277    5471         1.548
 281    7673         1.602
 283    773          1.187
 293    10987        1.654
 307    3643         1.453
 311    331          1.024
 313    3533         1.437
 317    8111         1.578
 331    6427         1.532
 337    2441         1.358
 347    1627         1.284
 349    9829         1.591
 353    937          1.180
 359    4973         1.464
 367    373          1.015
 373    10501        1.583
 379    1327         1.226
 383    2711         1.344
 389    16481        1.646
 397    14717        1.622
 401    8093         1.517
 409    26777        1.714
 419    31271        1.736
 421    677          1.090
 431    31957        1.731
 433    2503         1.302
 439    42829        1.771
 443    5519         1.427
 449    57089        1.810
 457    6491         1.447
 461    1021         1.139
 463    27919        1.680
 467    941          1.121
 479    22441        1.636
 487    54091        1.776
 491    10987        1.513
 499    691          1.061
 503    17669        1.584
 509    27527        1.652
 521    20731        1.603
 523    4001         1.335
 541    18859        1.581
 547    3457         1.306
 557    13337        1.520
 563    75391        1.793
 569    25237        1.615
 571    29077        1.635
 577    11593        1.486
 587    11483        1.481
 593    10691        1.467
 599    11777        1.480
 601    21149        1.570
 607    162527       1.888
 613    66403        1.744
 617    31991        1.626
 619    60889        1.724
 631    5179         1.336
 641    67411        1.735
 643    6329         1.363
 647    7907         1.396
 653    12437        1.464
 659    6803         1.368
 661    2423         1.206
 673    21269        1.540
 677    92503        1.764
 683    11321        1.438
 691    117571       1.796
 701    57649        1.683
 709    124781       1.799
 719    29833        1.578
 727    53093        1.663
 733    17851        1.495
 739    149159       1.816
 743    12157        1.432
 751    46441        1.634
 757    3919         1.256
 761    51563        1.645
 769    3677         1.243
 773    35117        1.582
 787    86981        1.717
 797    3607         1.235
 809    25847        1.530
 811    78511        1.695
 821    18301        1.474
 823    23509        1.510
 827    37663        1.578
 829    97813        1.719
 839    90697        1.706
 853    56393        1.633
 857    109253       1.729
 859    32371        1.546
 863    26347        1.514
 877    67217        1.651
 881    35521        1.554
 883    113843       1.725
 887    47581        1.594
 907    36161        1.551
 911    3407         1.201
 919    35257        1.544
 929    16417        1.430
 937    25577        1.493
 941    11933        1.380
 947    140159       1.740
 953    26203        1.492
 967    170921       1.765
 971    27827        1.498
 977    12157        1.375
 983    252727       1.816
 991    2011         1.109
 997    37813        1.536
Notice that the exponent is never greater than 2, so all numbers Q in this list are prime.
alpertron is offline   Reply With Quote
Old 2005-07-26, 00:27   #16
alpertron
 
alpertron's Avatar
 
Aug 2002
Buenos Aires, Argentina

22·3·53 Posts
Default

Quote:
Originally Posted by R.D. Silverman
Here's what makes me think the conjecture is probably false.

Put N = p#. The probability that N+Q is prime is about 1/log(N+Q) ~ 1/p
The probability that N-Q is also prime is ~1/p. We want to search over
values of Q, so that both are prime. If we let Q go from 1 to K,
then the probability of finding both prime for some Q is

sum from Q = 1 to k of 1/p^2 and this is just k/p^2 which is small.
for k ~ log^2 N. I expect that for some p's we will have to take k to
be bigger than log^2 N, i.e. Q will be p1*p2 for p1,p2 > p.

The problem is that 1/p^2 is quite small for large p.
Bob, please correct if I'm wrong.

p# is not a random number. It is multiple of all numbers from 1 to p.

So if gcd(Q, p#) = 1, it is true that gcd(p# + Q, p#) = 1.

Since p# + Q does not have any divisor less than or equal to p, the probability that p# + Q is prime should be much greater than T + Q when T is a random number near p#. The same argument can be said for p# - Q.
alpertron is offline   Reply With Quote
Old 2005-07-26, 04:53   #17
AntonVrba
 
AntonVrba's Avatar
 
Jun 2005

2×72 Posts
Default

First of all, fast and great work in producing that table up to 997#

Quote:
Originally Posted by alpertron
Notice that the exponent is never greater than 2, so all numbers Q in this list are prime..
.
On what basis is above statement made?



Quote:
Originally Posted by alpertron
Bob, please correct if I'm wrong.
So if gcd(Q, p#) = 1, it is true that gcd(p# + Q, p#) = 1.
.
You are not wrong - just logic. You can also say

If gcd(Q,p#)=x then gcd(p# + Q, p#) = x.

Last fiddled with by AntonVrba on 2005-07-26 at 04:59
AntonVrba is offline   Reply With Quote
Old 2005-07-26, 10:18   #18
AntonVrba
 
AntonVrba's Avatar
 
Jun 2005

6216 Posts
Default

I found following:
Quote:
http://mathworld.wolfram.com/EuclidsTheorems.html

Guy (1981, 1988) points out that while p1 p2…pn+1 is not necessarily prime, letting q be the next prime after p1 p2…pn +1, the number q – p1 p2…pn+1 is almost always a prime, although it has not been proven that this must always be the case.
Ignoring the obvious error of +1 it is much the same as I have conjectured here.

Last fiddled with by AntonVrba on 2005-07-26 at 10:22
AntonVrba is offline   Reply With Quote
Old 2005-07-26, 12:05   #19
alpertron
 
alpertron's Avatar
 
Aug 2002
Buenos Aires, Argentina

27348 Posts
Default

Since both p# + Q and p# - Q are prime, Q has no divisor less than or equal to p.

So if p2 < Q => ln Q / ln p < 2 the number Q must be prime (this is the basis for the trial division method). My error was to compute ln(Q)/ln(ln(p#)). The correct numbers are even lower than the numbers I computed yesterday:

Code:
 p      Q         ln(Q)/ln(p)
 5      7            1.209
 7      13           1.318
 11     23           1.308
 13     17           1.105
 17     59           1.439
 19     23           1.065
 23     79           1.394
 29     101          1.371
 31     83           1.287
 37     239          1.517
 41     71           1.148
 43     149          1.330
 47     367          1.534
 53     73           1.081
 59     911          1.671
 61     313          1.398
 67     373          1.408
 71     523          1.468
 73     313          1.339
 79     331          1.328
 83     197          1.196
 89     101          1.028
 97     1493         1.598
 101    523          1.356
 103    293          1.226
 107    577          1.361
 109    2699         1.684
 113    1481         1.544
 127    1453         1.503
 131    5647         1.772
 137    647          1.316
 139    419          1.224
 149    757          1.325
 151    4253         1.665
 157    509          1.233
 163    239          1.075
 167    10499        1.809
 173    191          1.019
 179    4013         1.600
 181    2659         1.517
 191    617          1.223
 193    6733         1.675
 197    1297         1.357
 199    971          1.299
 211    10093        1.723
 223    313          1.063
 227    1871         1.389
 229    883          1.248
 233    443          1.118
 239    1009         1.263
 241    1471         1.330
 251    12689        1.710
 257    2861         1.434
 263    8231         1.618
 269    7127         1.586
 271    1217         1.268
 277    5471         1.530
 281    7673         1.587
 283    773          1.178
 293    10987        1.638
 307    3643         1.432
 311    331          1.011
 313    3533         1.422
 317    8111         1.563
 331    6427         1.511
 337    2441         1.340
 347    1627         1.264
 349    9829         1.570
 353    937          1.166
 359    4973         1.447
 367    373          1.003
 373    10501        1.564
 379    1327         1.211
 383    2711         1.329
 389    16481        1.628
 397    14717        1.604
 401    8093         1.501
 409    26777        1.695
 419    31271        1.714
 421    677          1.079
 431    31957        1.710
 433    2503         1.289
 439    42829        1.753
 443    5519         1.414
 449    57089        1.793
 457    6491         1.433
 461    1021         1.130
 463    27919        1.668
 467    941          1.114
 479    22441        1.623
 487    54091        1.761
 491    10987        1.502
 499    691          1.052
 503    17669        1.572
 509    27527        1.640
 521    20731        1.589
 523    4001         1.325
 541    18859        1.564
 547    3457         1.292
 557    13337        1.502
 563    75391        1.773
 569    25237        1.598
 571    29077        1.619
 577    11593        1.472
 587    11483        1.466
 593    10691        1.453
 599    11777        1.466
 601    21149        1.556
 607    162527       1.872
 613    66403        1.730
 617    31991        1.615
 619    60889        1.714
 631    5179         1.327
 641    67411        1.720
 643    6329         1.354
 647    7907         1.387
 653    12437        1.455
 659    6803         1.360
 661    2423         1.200
 673    21269        1.530
 677    92503        1.754
 683    11321        1.430
 691    117571       1.786
 701    57649        1.673
 709    124781       1.788
 719    29833        1.566
 727    53093        1.651
 733    17851        1.484
 739    149159       1.804
 743    12157        1.423
 751    46441        1.623
 757    3919         1.248
 761    51563        1.635
 769    3677         1.235
 773    35117        1.574
 787    86981        1.706
 797    3607         1.226
 809    25847        1.517
 811    78511        1.683
 821    18301        1.463
 823    23509        1.499
 827    37663        1.568
 829    97813        1.710
 839    90697        1.696
 853    56393        1.621
 857    109253       1.718
 859    32371        1.537
 863    26347        1.506
 877    67217        1.640
 881    35521        1.545
 883    113843       1.716
 887    47581        1.587
 907    36161        1.541
 911    3407         1.194
 919    35257        1.535
 929    16417        1.420
 937    25577        1.483
 941    11933        1.371
 947    140159       1.729
 953    26203        1.483
 967    170921       1.753
 971    27827        1.488
 977    12157        1.366
 983    252727       1.805
 991    2011         1.103
 997    37813        1.527
The question was not about the third sentence (which is obvious), but about the last one. Sorry for my bad English.
alpertron is offline   Reply With Quote
Old 2005-07-26, 12:49   #20
AntonVrba
 
AntonVrba's Avatar
 
Jun 2005

2×72 Posts
Default

Quote:
Originally Posted by alpertron
The question was not about the third sentence (which is obvious), but about the last one. Sorry for my bad English.
Lets have a argument - your bad english vs my sloppy reading - your english is not bad - sorry for mis-reading

Quote:
Originally Posted by alpertron
Since p# + Q does not have any divisor less than or equal to p, the probability that p# + Q is prime should be much greater than T + Q when T is a random number near p#. The same argument can be said for p# - Q..
Yes, I believe that centred around p# a region of prime rich clusters and the large gap conjectured by Cramer will not be found here.
AntonVrba is offline   Reply With Quote
Reply

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Prime conjecture Stan Math 42 2021-05-23 17:09
Goldbach Conjecture MattcAnderson MattcAnderson 4 2021-04-04 19:21
This conjecture may be useful. reddwarf2956 Prime Gap Searches 2 2016-03-01 22:41
Saari's Conjecture Zeta-Flux Science & Technology 0 2012-10-10 15:43
Conjecture devarajkandadai Math 13 2012-05-27 07:38

All times are UTC. The time now is 22:30.


Tue Mar 28 22:30:42 UTC 2023 up 222 days, 19:59, 0 users, load averages: 0.59, 0.80, 0.90

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.

≠ ± ∓ ÷ × · − √ ‰ ⊗ ⊕ ⊖ ⊘ ⊙ ≤ ≥ ≦ ≧ ≨ ≩ ≺ ≻ ≼ ≽ ⊏ ⊐ ⊑ ⊒ ² ³ °
∠ ∟ ° ≅ ~ ‖ ⟂ ⫛
≡ ≜ ≈ ∝ ∞ ≪ ≫ ⌊⌋ ⌈⌉ ∘ ∏ ∐ ∑ ∧ ∨ ∩ ∪ ⨀ ⊕ ⊗ 𝖕 𝖖 𝖗 ⊲ ⊳
∅ ∖ ∁ ↦ ↣ ∩ ∪ ⊆ ⊂ ⊄ ⊊ ⊇ ⊃ ⊅ ⊋ ⊖ ∈ ∉ ∋ ∌ ℕ ℤ ℚ ℝ ℂ ℵ ℶ ℷ ℸ 𝓟
¬ ∨ ∧ ⊕ → ← ⇒ ⇐ ⇔ ∀ ∃ ∄ ∴ ∵ ⊤ ⊥ ⊢ ⊨ ⫤ ⊣ … ⋯ ⋮ ⋰ ⋱
∫ ∬ ∭ ∮ ∯ ∰ ∇ ∆ δ ∂ ℱ ℒ ℓ
𝛢𝛼 𝛣𝛽 𝛤𝛾 𝛥𝛿 𝛦𝜀𝜖 𝛧𝜁 𝛨𝜂 𝛩𝜃𝜗 𝛪𝜄 𝛫𝜅 𝛬𝜆 𝛭𝜇 𝛮𝜈 𝛯𝜉 𝛰𝜊 𝛱𝜋 𝛲𝜌 𝛴𝜎𝜍 𝛵𝜏 𝛶𝜐 𝛷𝜙𝜑 𝛸𝜒 𝛹𝜓 𝛺𝜔