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A conjecture about number 641



The 2019 Stack Overflow Developer Survey Results Are InWeak version of Fortune's conjectureA different approach to the strong Goldbach conjecture?Proof of Prime Maker ConjectureSome questions about Goldbach's conjectureIs my conjecture true? : Every primorial is a superior highly regular number, and every superior highly regular number is a primorial.Is 641 the Smallest Factor of any Composite Fermat Number?Is every primorial number squarefree?Conjecture concerning modular arithmeticConjecture about the prime number functionExpected size of the maximal prime gap below x under Hardy-Littlewood conjecture










0












$begingroup$


I conjecture that $233#-1$ is the only number of the form $p#-1$, where p is a prime and # denotes the primorial function, which is divisibile by $641$. $641$ is the smallest prime dividing $F_5$, as shown by Euler.










share|cite|improve this question











$endgroup$











  • $begingroup$
    @Peter could you disproof the conjecture?
    $endgroup$
    – homunculus
    Mar 30 at 11:41






  • 2




    $begingroup$
    The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
    $endgroup$
    – Mann
    Mar 30 at 11:47











  • $begingroup$
    @Mann can you find another prime p such that p#-1 is divisibile by 641?
    $endgroup$
    – homunculus
    Mar 30 at 11:50











  • $begingroup$
    No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
    $endgroup$
    – Mann
    Mar 30 at 11:52
















0












$begingroup$


I conjecture that $233#-1$ is the only number of the form $p#-1$, where p is a prime and # denotes the primorial function, which is divisibile by $641$. $641$ is the smallest prime dividing $F_5$, as shown by Euler.










share|cite|improve this question











$endgroup$











  • $begingroup$
    @Peter could you disproof the conjecture?
    $endgroup$
    – homunculus
    Mar 30 at 11:41






  • 2




    $begingroup$
    The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
    $endgroup$
    – Mann
    Mar 30 at 11:47











  • $begingroup$
    @Mann can you find another prime p such that p#-1 is divisibile by 641?
    $endgroup$
    – homunculus
    Mar 30 at 11:50











  • $begingroup$
    No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
    $endgroup$
    – Mann
    Mar 30 at 11:52














0












0








0





$begingroup$


I conjecture that $233#-1$ is the only number of the form $p#-1$, where p is a prime and # denotes the primorial function, which is divisibile by $641$. $641$ is the smallest prime dividing $F_5$, as shown by Euler.










share|cite|improve this question











$endgroup$




I conjecture that $233#-1$ is the only number of the form $p#-1$, where p is a prime and # denotes the primorial function, which is divisibile by $641$. $641$ is the smallest prime dividing $F_5$, as shown by Euler.







number-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Mar 30 at 12:02







homunculus

















asked Mar 30 at 11:37









homunculushomunculus

17410




17410











  • $begingroup$
    @Peter could you disproof the conjecture?
    $endgroup$
    – homunculus
    Mar 30 at 11:41






  • 2




    $begingroup$
    The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
    $endgroup$
    – Mann
    Mar 30 at 11:47











  • $begingroup$
    @Mann can you find another prime p such that p#-1 is divisibile by 641?
    $endgroup$
    – homunculus
    Mar 30 at 11:50











  • $begingroup$
    No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
    $endgroup$
    – Mann
    Mar 30 at 11:52

















  • $begingroup$
    @Peter could you disproof the conjecture?
    $endgroup$
    – homunculus
    Mar 30 at 11:41






  • 2




    $begingroup$
    The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
    $endgroup$
    – Mann
    Mar 30 at 11:47











  • $begingroup$
    @Mann can you find another prime p such that p#-1 is divisibile by 641?
    $endgroup$
    – homunculus
    Mar 30 at 11:50











  • $begingroup$
    No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
    $endgroup$
    – Mann
    Mar 30 at 11:52
















$begingroup$
@Peter could you disproof the conjecture?
$endgroup$
– homunculus
Mar 30 at 11:41




$begingroup$
@Peter could you disproof the conjecture?
$endgroup$
– homunculus
Mar 30 at 11:41




2




2




$begingroup$
The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
$endgroup$
– Mann
Mar 30 at 11:47





$begingroup$
The only thing I see about $641$ is that it's prime and it's a factor of $F5$, the 5th Fermat's number. If that's the case, I am not really sure why this type of conjecture should be unique to $641$, if it is indeed true.
$endgroup$
– Mann
Mar 30 at 11:47













$begingroup$
@Mann can you find another prime p such that p#-1 is divisibile by 641?
$endgroup$
– homunculus
Mar 30 at 11:50





$begingroup$
@Mann can you find another prime p such that p#-1 is divisibile by 641?
$endgroup$
– homunculus
Mar 30 at 11:50













$begingroup$
No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
$endgroup$
– Mann
Mar 30 at 11:52





$begingroup$
No, what I mean is. What is unique about the conjecture $p' # - 1$ divisible by some prime $p_0$. If it's for $641$, can't I take some other values? What makes you think $641$ and $233$ are unique? This could help us proceed.
$endgroup$
– Mann
Mar 30 at 11:52











1 Answer
1






active

oldest

votes


















3












$begingroup$

It is true, but I doubt there's any significance to it. The number $p# - 1$ is clearly not divisible by $641$ if $pgeq 641$, and it turns out that $233# equiv 1pmod641$. Similarly, $3#1 - 1 = 5$ is divisible by $5$; and $7#-1 = 209$ is divisible by $11$ and $19$; and etc.






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    1 Answer
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    1 Answer
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    active

    oldest

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    3












    $begingroup$

    It is true, but I doubt there's any significance to it. The number $p# - 1$ is clearly not divisible by $641$ if $pgeq 641$, and it turns out that $233# equiv 1pmod641$. Similarly, $3#1 - 1 = 5$ is divisible by $5$; and $7#-1 = 209$ is divisible by $11$ and $19$; and etc.






    share|cite|improve this answer









    $endgroup$

















      3












      $begingroup$

      It is true, but I doubt there's any significance to it. The number $p# - 1$ is clearly not divisible by $641$ if $pgeq 641$, and it turns out that $233# equiv 1pmod641$. Similarly, $3#1 - 1 = 5$ is divisible by $5$; and $7#-1 = 209$ is divisible by $11$ and $19$; and etc.






      share|cite|improve this answer









      $endgroup$















        3












        3








        3





        $begingroup$

        It is true, but I doubt there's any significance to it. The number $p# - 1$ is clearly not divisible by $641$ if $pgeq 641$, and it turns out that $233# equiv 1pmod641$. Similarly, $3#1 - 1 = 5$ is divisible by $5$; and $7#-1 = 209$ is divisible by $11$ and $19$; and etc.






        share|cite|improve this answer









        $endgroup$



        It is true, but I doubt there's any significance to it. The number $p# - 1$ is clearly not divisible by $641$ if $pgeq 641$, and it turns out that $233# equiv 1pmod641$. Similarly, $3#1 - 1 = 5$ is divisible by $5$; and $7#-1 = 209$ is divisible by $11$ and $19$; and etc.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Mar 30 at 12:28









        anomalyanomaly

        17.8k42666




        17.8k42666



























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