Given an odd integer, $a$ does $gcd(a,p-1)=1$ has infinitely many prime $p$ solutions?












2












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Given an odd integer, $a$ does $gcd(a,p-1)=1$ has infinitely many prime $p$ solutions?



One can argue that there are infinitely many numbers $x$ satisfies $gcd(a,$x$)=1$. How to argue that there are infinitely many prime $p=x+1$.



Any hint?










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  • 2




    $begingroup$
    When $a=2$ this asks: are there infinitely many even primes?
    $endgroup$
    – GEdgar
    Dec 4 '18 at 22:38






  • 3




    $begingroup$
    If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 22:38










  • $begingroup$
    let me correct to odd.
    $endgroup$
    – kelalaka
    Dec 4 '18 at 22:39
















2












$begingroup$


Given an odd integer, $a$ does $gcd(a,p-1)=1$ has infinitely many prime $p$ solutions?



One can argue that there are infinitely many numbers $x$ satisfies $gcd(a,$x$)=1$. How to argue that there are infinitely many prime $p=x+1$.



Any hint?










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    When $a=2$ this asks: are there infinitely many even primes?
    $endgroup$
    – GEdgar
    Dec 4 '18 at 22:38






  • 3




    $begingroup$
    If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 22:38










  • $begingroup$
    let me correct to odd.
    $endgroup$
    – kelalaka
    Dec 4 '18 at 22:39














2












2








2





$begingroup$


Given an odd integer, $a$ does $gcd(a,p-1)=1$ has infinitely many prime $p$ solutions?



One can argue that there are infinitely many numbers $x$ satisfies $gcd(a,$x$)=1$. How to argue that there are infinitely many prime $p=x+1$.



Any hint?










share|cite|improve this question











$endgroup$




Given an odd integer, $a$ does $gcd(a,p-1)=1$ has infinitely many prime $p$ solutions?



One can argue that there are infinitely many numbers $x$ satisfies $gcd(a,$x$)=1$. How to argue that there are infinitely many prime $p=x+1$.



Any hint?







prime-numbers greatest-common-divisor






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share|cite|improve this question













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share|cite|improve this question








edited Dec 4 '18 at 22:39







kelalaka

















asked Dec 4 '18 at 22:31









kelalakakelalaka

3301312




3301312








  • 2




    $begingroup$
    When $a=2$ this asks: are there infinitely many even primes?
    $endgroup$
    – GEdgar
    Dec 4 '18 at 22:38






  • 3




    $begingroup$
    If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 22:38










  • $begingroup$
    let me correct to odd.
    $endgroup$
    – kelalaka
    Dec 4 '18 at 22:39














  • 2




    $begingroup$
    When $a=2$ this asks: are there infinitely many even primes?
    $endgroup$
    – GEdgar
    Dec 4 '18 at 22:38






  • 3




    $begingroup$
    If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
    $endgroup$
    – Daniel Schepler
    Dec 4 '18 at 22:38










  • $begingroup$
    let me correct to odd.
    $endgroup$
    – kelalaka
    Dec 4 '18 at 22:39








2




2




$begingroup$
When $a=2$ this asks: are there infinitely many even primes?
$endgroup$
– GEdgar
Dec 4 '18 at 22:38




$begingroup$
When $a=2$ this asks: are there infinitely many even primes?
$endgroup$
– GEdgar
Dec 4 '18 at 22:38




3




3




$begingroup$
If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
$endgroup$
– Daniel Schepler
Dec 4 '18 at 22:38




$begingroup$
If $a$ is even, no... But if $a$ is odd, my hint would be to apply the Dirichlet arithmetic progression theorem.
$endgroup$
– Daniel Schepler
Dec 4 '18 at 22:38












$begingroup$
let me correct to odd.
$endgroup$
– kelalaka
Dec 4 '18 at 22:39




$begingroup$
let me correct to odd.
$endgroup$
– kelalaka
Dec 4 '18 at 22:39










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$begingroup$

By Dirichlet's theorem, there are infinitely many primes in the arithmetic series $2+na$, ($nin mathbb{N}$).
If $p=2+na$ is such a prime, then $gcd(a, p-1) = gcd(a, 1+na) = 1$.






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    1 Answer
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    $begingroup$

    By Dirichlet's theorem, there are infinitely many primes in the arithmetic series $2+na$, ($nin mathbb{N}$).
    If $p=2+na$ is such a prime, then $gcd(a, p-1) = gcd(a, 1+na) = 1$.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      By Dirichlet's theorem, there are infinitely many primes in the arithmetic series $2+na$, ($nin mathbb{N}$).
      If $p=2+na$ is such a prime, then $gcd(a, p-1) = gcd(a, 1+na) = 1$.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        By Dirichlet's theorem, there are infinitely many primes in the arithmetic series $2+na$, ($nin mathbb{N}$).
        If $p=2+na$ is such a prime, then $gcd(a, p-1) = gcd(a, 1+na) = 1$.






        share|cite|improve this answer









        $endgroup$



        By Dirichlet's theorem, there are infinitely many primes in the arithmetic series $2+na$, ($nin mathbb{N}$).
        If $p=2+na$ is such a prime, then $gcd(a, p-1) = gcd(a, 1+na) = 1$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 4 '18 at 22:45









        A. PongráczA. Pongrácz

        5,9631929




        5,9631929






























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