number of coprimes to a less than b Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)Count Integers Not Greater Than $a$ Coprime To $b$Variation on euler totient/phi functionCo Prime Numbers less than NNumber of coprimes of $n$ divisible by 3Calculation of product of all coprimes of number less than itselfHow to count the number of perfect square greater than $N$ and less than $N^2$ that are relatively prime to $N$?All numbers less than 100 with phi(n) = 64How many numbers less than $m$ and relatively prime to $n$, where $m>n$?Number of integers (less than $n$) that are divisible by a prime factor of $n$Are there any known methods for finding Upper/Lower bounds on the number of Totients of x less than another number y?Find taxicab numbers in less than $O(n^2)$ time with number theory into consideration

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number of coprimes to a less than b



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)Count Integers Not Greater Than $a$ Coprime To $b$Variation on euler totient/phi functionCo Prime Numbers less than NNumber of coprimes of $n$ divisible by 3Calculation of product of all coprimes of number less than itselfHow to count the number of perfect square greater than $N$ and less than $N^2$ that are relatively prime to $N$?All numbers less than 100 with phi(n) = 64How many numbers less than $m$ and relatively prime to $n$, where $m>n$?Number of integers (less than $n$) that are divisible by a prime factor of $n$Are there any known methods for finding Upper/Lower bounds on the number of Totients of x less than another number y?Find taxicab numbers in less than $O(n^2)$ time with number theory into consideration










0












$begingroup$


We know that number of coprimes less than a number can be found using euler function https://brilliant.org/wiki/eulers-totient-function/ But if there are two numbers p,q and we need to find number of numbers less than q and coprime to p. Is there any efficient method ? can we develop an algorithm.










share|cite|improve this question









$endgroup$







  • 1




    $begingroup$
    Which is greater, $p$ or $q$? It does matter.
    $endgroup$
    – ajotatxe
    Apr 2 at 17:41










  • $begingroup$
    We have both the cases. p<q and p>q as well.
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 17:42







  • 1




    $begingroup$
    Answered here: math.stackexchange.com/a/3158036/181098
    $endgroup$
    – W-t-P
    Apr 2 at 18:02










  • $begingroup$
    @W-t-P Can you give a simple,actual example how to calculate ?
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 18:14







  • 1




    $begingroup$
    You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
    $endgroup$
    – W-t-P
    Apr 2 at 18:38
















0












$begingroup$


We know that number of coprimes less than a number can be found using euler function https://brilliant.org/wiki/eulers-totient-function/ But if there are two numbers p,q and we need to find number of numbers less than q and coprime to p. Is there any efficient method ? can we develop an algorithm.










share|cite|improve this question









$endgroup$







  • 1




    $begingroup$
    Which is greater, $p$ or $q$? It does matter.
    $endgroup$
    – ajotatxe
    Apr 2 at 17:41










  • $begingroup$
    We have both the cases. p<q and p>q as well.
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 17:42







  • 1




    $begingroup$
    Answered here: math.stackexchange.com/a/3158036/181098
    $endgroup$
    – W-t-P
    Apr 2 at 18:02










  • $begingroup$
    @W-t-P Can you give a simple,actual example how to calculate ?
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 18:14







  • 1




    $begingroup$
    You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
    $endgroup$
    – W-t-P
    Apr 2 at 18:38














0












0








0





$begingroup$


We know that number of coprimes less than a number can be found using euler function https://brilliant.org/wiki/eulers-totient-function/ But if there are two numbers p,q and we need to find number of numbers less than q and coprime to p. Is there any efficient method ? can we develop an algorithm.










share|cite|improve this question









$endgroup$




We know that number of coprimes less than a number can be found using euler function https://brilliant.org/wiki/eulers-totient-function/ But if there are two numbers p,q and we need to find number of numbers less than q and coprime to p. Is there any efficient method ? can we develop an algorithm.







number-theory prime-numbers algorithms prime-factorization totient-function






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Apr 2 at 17:38









Manoharsinh RanaManoharsinh Rana

116




116







  • 1




    $begingroup$
    Which is greater, $p$ or $q$? It does matter.
    $endgroup$
    – ajotatxe
    Apr 2 at 17:41










  • $begingroup$
    We have both the cases. p<q and p>q as well.
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 17:42







  • 1




    $begingroup$
    Answered here: math.stackexchange.com/a/3158036/181098
    $endgroup$
    – W-t-P
    Apr 2 at 18:02










  • $begingroup$
    @W-t-P Can you give a simple,actual example how to calculate ?
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 18:14







  • 1




    $begingroup$
    You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
    $endgroup$
    – W-t-P
    Apr 2 at 18:38













  • 1




    $begingroup$
    Which is greater, $p$ or $q$? It does matter.
    $endgroup$
    – ajotatxe
    Apr 2 at 17:41










  • $begingroup$
    We have both the cases. p<q and p>q as well.
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 17:42







  • 1




    $begingroup$
    Answered here: math.stackexchange.com/a/3158036/181098
    $endgroup$
    – W-t-P
    Apr 2 at 18:02










  • $begingroup$
    @W-t-P Can you give a simple,actual example how to calculate ?
    $endgroup$
    – Manoharsinh Rana
    Apr 2 at 18:14







  • 1




    $begingroup$
    You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
    $endgroup$
    – W-t-P
    Apr 2 at 18:38








1




1




$begingroup$
Which is greater, $p$ or $q$? It does matter.
$endgroup$
– ajotatxe
Apr 2 at 17:41




$begingroup$
Which is greater, $p$ or $q$? It does matter.
$endgroup$
– ajotatxe
Apr 2 at 17:41












$begingroup$
We have both the cases. p<q and p>q as well.
$endgroup$
– Manoharsinh Rana
Apr 2 at 17:42





$begingroup$
We have both the cases. p<q and p>q as well.
$endgroup$
– Manoharsinh Rana
Apr 2 at 17:42





1




1




$begingroup$
Answered here: math.stackexchange.com/a/3158036/181098
$endgroup$
– W-t-P
Apr 2 at 18:02




$begingroup$
Answered here: math.stackexchange.com/a/3158036/181098
$endgroup$
– W-t-P
Apr 2 at 18:02












$begingroup$
@W-t-P Can you give a simple,actual example how to calculate ?
$endgroup$
– Manoharsinh Rana
Apr 2 at 18:14





$begingroup$
@W-t-P Can you give a simple,actual example how to calculate ?
$endgroup$
– Manoharsinh Rana
Apr 2 at 18:14





1




1




$begingroup$
You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
$endgroup$
– W-t-P
Apr 2 at 18:38





$begingroup$
You have a very explicit formula: $sum_dmid a mu(d) lfloor b/drfloor$. Here $d$ runs over all positive divisors of $a$ (including $1$ and $a$), $mu$ is the Mobious function, and $lfloor b/drfloor$ is the largest integer not exceeding $b/d$. I am afraid I cannot explain anything beyond this.
$endgroup$
– W-t-P
Apr 2 at 18:38











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