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(mention which case is already proven; mention Sierpiński problem as well; avoid "here" link)
 
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The '''Liskovets-Gallot conjectures''' are a family of conjectures regarding the frequency of prime {{Vn}}-values of a given parity for Riesel and Proth {{Vk}}-values divisible by 3. The notion that certain {{Vk}}-values, divisible by 3, have no prime {{Vn}}-values of a given parity was first conjectured by [[Valery Liskovets]] in 2001. [[Yves Gallot]] found suitable non-trivial {{Vk}}-values for all four sign/parity combinations shortly thereafter and claimed them to be the smallest such {{Vk}}-values, thus forming the conjectures' final form. A search was started by [[Conjectures 'R Us|CRUS]] in 2008 to prove the conjectures by finding primes of the required parity for all smaller {{Vk}}-values. The even Proth conjecture was proven in 2015, and CRUS is continuing the [[CRUS Liskovets-Gallot]] subproject to find the remaining 9 primes required to prove the other 3 conjectures.
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==Definitions==
 
==Definitions==
[[Valery Liskovets]] studied the list of {{Kbn|+|k|n}} primes and observed, that the k's (k divisible by 3)
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[[Valery Liskovets]] studied the list of {{Kbn|+|k|n}} primes and observed, that the {{Vk}}'s ({{Vk}} divisible by 3)
 
got an irregular contribution of odd and even exponents yielding a prime.
 
got an irregular contribution of odd and even exponents yielding a prime.
  
Examples: (for 1 <= n <= 100000)
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Examples: (for 1 ≤ {{Vn}} ≤ 100000)
 
{| class="wikitable"
 
{| class="wikitable"
!k-value!!# odd!!# even
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!{{Vk}}-value!!# odd!!# even
 
|-
 
|-
 
|51||38||5
 
|51||38||5
Line 23: Line 25:
  
 
So Liskovets formulated the conjecture:
 
So Liskovets formulated the conjecture:
:'''"There exist k, 3|k, such that primes {{Kbn|+|k|n}} do exist but only with odd n /only with even n."'''
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<blockquote>'''There exist {{Vk}}, 3|{{Vk}}, such that primes {{Kbn|+|k|n}} do exist but only with odd {{Vn}}/only with even {{Vn}}.'''</blockquote>
  
 
[[Yves Gallot]] extended this for {{Kbn|k|n}} numbers and gave also the first solutions as:
 
[[Yves Gallot]] extended this for {{Kbn|k|n}} numbers and gave also the first solutions as:
  
:{{Kbn|+|k|n}} is composite for all n=even: '''k=66741'''
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:{{Kbn|+|k|n}} is composite for all even {{Vn}} for {{Vk}}=[[Proth prime 2 66741|66741]] (proven minimal in 2015)
:{{Kbn|+|k|n}} is composite for all n=odd: '''k=95283'''
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:{{Kbn|+|k|n}} is composite for all odd {{Vn}} for {{Vk}}=[[Proth prime 2 95283|95283]]
:{{Kbn|k|n}} is composite for all n=even: '''k=39939'''
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:{{Kbn|k|n}} is composite for all even {{Vn}} for {{Vk}}=[[Riesel prime 2 39939|39939]]
:{{Kbn|k|n}} is composite for all n=odd: '''k=172677'''
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:{{Kbn|k|n}} is composite for all odd {{Vn}} for {{Vk}}=[[Riesel prime 2 172677|172677]]
  
 
==Proof==
 
==Proof==
The verification of these conjectures has to be done in the same manner like the [[Riesel problem]]: find a prime for all k-values less than the given with the needed condition.
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The verification of these conjectures has to be done in the same manner as the [[Riesel problem 1|Riesel]] and [[Sierpiński problem]]s: find a prime for all {{Vk}}-values less than the given with the needed condition.
  
 
==Search==
 
==Search==
The current search is maintaind by the [[Conjectures 'R Us]] project and can be found [[CRUS Liskovets-Gallot|here]].
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The current search is maintained by the [[Conjectures 'R Us]] project and described in the article [[CRUS Liskovets-Gallot]].
  
 
==Links==
 
==Links==
 
*[https://www.primepuzzles.net/problems/prob_036.htm Problem 36] "The Liskovets-Gallot numbers" from [https://www.primepuzzles.net/index.shtml PP&P connection] by [[Carlos Rivera]]
 
*[https://www.primepuzzles.net/problems/prob_036.htm Problem 36] "The Liskovets-Gallot numbers" from [https://www.primepuzzles.net/index.shtml PP&P connection] by [[Carlos Rivera]]
[[Category:Math]]
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[[Category:Conjectures]]

Latest revision as of 12:42, 9 May 2024

The Liskovets-Gallot conjectures are a family of conjectures regarding the frequency of prime n-values of a given parity for Riesel and Proth k-values divisible by 3. The notion that certain k-values, divisible by 3, have no prime n-values of a given parity was first conjectured by Valery Liskovets in 2001. Yves Gallot found suitable non-trivial k-values for all four sign/parity combinations shortly thereafter and claimed them to be the smallest such k-values, thus forming the conjectures' final form. A search was started by CRUS in 2008 to prove the conjectures by finding primes of the required parity for all smaller k-values. The even Proth conjecture was proven in 2015, and CRUS is continuing the CRUS Liskovets-Gallot subproject to find the remaining 9 primes required to prove the other 3 conjectures.

Definitions

Valery Liskovets studied the list of k•2n+1 primes and observed, that the k's (k divisible by 3) got an irregular contribution of odd and even exponents yielding a prime.

Examples: (for 1 ≤ n ≤ 100000)

k-value # odd # even
51 38 5
231 51 9
261 56 14
87 2 36
93 1 38
177 8 46

So Liskovets formulated the conjecture:

There exist k, 3|k, such that primes k•2n+1 do exist but only with odd n/only with even n.

Yves Gallot extended this for k•2n-1 numbers and gave also the first solutions as:

k•2n+1 is composite for all even n for k=66741 (proven minimal in 2015)
k•2n+1 is composite for all odd n for k=95283
k•2n-1 is composite for all even n for k=39939
k•2n-1 is composite for all odd n for k=172677

Proof

The verification of these conjectures has to be done in the same manner as the Riesel and Sierpiński problems: find a prime for all k-values less than the given with the needed condition.

Search

The current search is maintained by the Conjectures 'R Us project and described in the article CRUS Liskovets-Gallot.

Links