A conjecture on the closeness of twin primes












3












$begingroup$



Let $p_1$ and $p_2$ be twin primes, and let $p_1-1=a_1times b_1$ and $p_2+1=a_2times b_2$ be such that $|b_1-a_1|$ and $|b_2-a_2|$ are minimised. Similarly, let $p_1+1=p_2-1=atimes b$ be such that $|b-a|$ is minimised.



Now assume the twin prime conjecture, and let $$mathcal P_n=frac{#text{twin primes} le n:min{|b_1-a_1|,|b-a|,|b_2-a_2|}neq|b-a|}{#text{twin primes} le n}$$ What is the value of $mathcal P_infty$?



Note that by convention the pair $(2,3)$ are not twin primes.




For twin primes less than $100$, we have that $p_1=5,17$. Hence I think that if there are infinitely many such primes then they will be exceedingly sparse.



Here is a table showing $mathcal P_n$ for increasing values of $n$. begin{array}{c|c}log_{10}n&1&2&3&4&5&6&7&8&9&10\hline mathcal P_n&frac12&frac14&frac{17}{35}&frac{93}{205}&frac{600}{1224}&frac{4326}{8169}&frac{31939}{58980}&frac{243876}{440312}&frac{1928700}{3424506}&frac{15661079}{27412679}\hlinetext{decimal}&small 0.5&small0.25&small0.4857&small0.4537&small0.4902&small0.5296&small0.5415&small0.5539&small0.5632&small0.5713end{array}



This can be seen more clearly in the following plot; more interesting is the behaviour after $n=10^4$.



enter image description here



There is a slight dip at $n=10^2,10^4$ but otherwise it looks like there is a converging increase in $mathcal P_n$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:12






  • 1




    $begingroup$
    As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:23










  • $begingroup$
    you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
    $endgroup$
    – Nick
    Sep 2 '18 at 19:43






  • 1




    $begingroup$
    Made a very simple Sage program to find them.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:01






  • 3




    $begingroup$
    Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:07
















3












$begingroup$



Let $p_1$ and $p_2$ be twin primes, and let $p_1-1=a_1times b_1$ and $p_2+1=a_2times b_2$ be such that $|b_1-a_1|$ and $|b_2-a_2|$ are minimised. Similarly, let $p_1+1=p_2-1=atimes b$ be such that $|b-a|$ is minimised.



Now assume the twin prime conjecture, and let $$mathcal P_n=frac{#text{twin primes} le n:min{|b_1-a_1|,|b-a|,|b_2-a_2|}neq|b-a|}{#text{twin primes} le n}$$ What is the value of $mathcal P_infty$?



Note that by convention the pair $(2,3)$ are not twin primes.




For twin primes less than $100$, we have that $p_1=5,17$. Hence I think that if there are infinitely many such primes then they will be exceedingly sparse.



Here is a table showing $mathcal P_n$ for increasing values of $n$. begin{array}{c|c}log_{10}n&1&2&3&4&5&6&7&8&9&10\hline mathcal P_n&frac12&frac14&frac{17}{35}&frac{93}{205}&frac{600}{1224}&frac{4326}{8169}&frac{31939}{58980}&frac{243876}{440312}&frac{1928700}{3424506}&frac{15661079}{27412679}\hlinetext{decimal}&small 0.5&small0.25&small0.4857&small0.4537&small0.4902&small0.5296&small0.5415&small0.5539&small0.5632&small0.5713end{array}



This can be seen more clearly in the following plot; more interesting is the behaviour after $n=10^4$.



enter image description here



There is a slight dip at $n=10^2,10^4$ but otherwise it looks like there is a converging increase in $mathcal P_n$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:12






  • 1




    $begingroup$
    As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:23










  • $begingroup$
    you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
    $endgroup$
    – Nick
    Sep 2 '18 at 19:43






  • 1




    $begingroup$
    Made a very simple Sage program to find them.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:01






  • 3




    $begingroup$
    Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:07














3












3








3


1



$begingroup$



Let $p_1$ and $p_2$ be twin primes, and let $p_1-1=a_1times b_1$ and $p_2+1=a_2times b_2$ be such that $|b_1-a_1|$ and $|b_2-a_2|$ are minimised. Similarly, let $p_1+1=p_2-1=atimes b$ be such that $|b-a|$ is minimised.



Now assume the twin prime conjecture, and let $$mathcal P_n=frac{#text{twin primes} le n:min{|b_1-a_1|,|b-a|,|b_2-a_2|}neq|b-a|}{#text{twin primes} le n}$$ What is the value of $mathcal P_infty$?



Note that by convention the pair $(2,3)$ are not twin primes.




For twin primes less than $100$, we have that $p_1=5,17$. Hence I think that if there are infinitely many such primes then they will be exceedingly sparse.



Here is a table showing $mathcal P_n$ for increasing values of $n$. begin{array}{c|c}log_{10}n&1&2&3&4&5&6&7&8&9&10\hline mathcal P_n&frac12&frac14&frac{17}{35}&frac{93}{205}&frac{600}{1224}&frac{4326}{8169}&frac{31939}{58980}&frac{243876}{440312}&frac{1928700}{3424506}&frac{15661079}{27412679}\hlinetext{decimal}&small 0.5&small0.25&small0.4857&small0.4537&small0.4902&small0.5296&small0.5415&small0.5539&small0.5632&small0.5713end{array}



This can be seen more clearly in the following plot; more interesting is the behaviour after $n=10^4$.



enter image description here



There is a slight dip at $n=10^2,10^4$ but otherwise it looks like there is a converging increase in $mathcal P_n$.










share|cite|improve this question











$endgroup$





Let $p_1$ and $p_2$ be twin primes, and let $p_1-1=a_1times b_1$ and $p_2+1=a_2times b_2$ be such that $|b_1-a_1|$ and $|b_2-a_2|$ are minimised. Similarly, let $p_1+1=p_2-1=atimes b$ be such that $|b-a|$ is minimised.



Now assume the twin prime conjecture, and let $$mathcal P_n=frac{#text{twin primes} le n:min{|b_1-a_1|,|b-a|,|b_2-a_2|}neq|b-a|}{#text{twin primes} le n}$$ What is the value of $mathcal P_infty$?



Note that by convention the pair $(2,3)$ are not twin primes.




For twin primes less than $100$, we have that $p_1=5,17$. Hence I think that if there are infinitely many such primes then they will be exceedingly sparse.



Here is a table showing $mathcal P_n$ for increasing values of $n$. begin{array}{c|c}log_{10}n&1&2&3&4&5&6&7&8&9&10\hline mathcal P_n&frac12&frac14&frac{17}{35}&frac{93}{205}&frac{600}{1224}&frac{4326}{8169}&frac{31939}{58980}&frac{243876}{440312}&frac{1928700}{3424506}&frac{15661079}{27412679}\hlinetext{decimal}&small 0.5&small0.25&small0.4857&small0.4537&small0.4902&small0.5296&small0.5415&small0.5539&small0.5632&small0.5713end{array}



This can be seen more clearly in the following plot; more interesting is the behaviour after $n=10^4$.



enter image description here



There is a slight dip at $n=10^2,10^4$ but otherwise it looks like there is a converging increase in $mathcal P_n$.







number-theory prime-numbers conjectures prime-twins






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 16 '18 at 15:44







TheSimpliFire

















asked Sep 2 '18 at 19:03









TheSimpliFireTheSimpliFire

12.5k62460




12.5k62460












  • $begingroup$
    Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:12






  • 1




    $begingroup$
    As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:23










  • $begingroup$
    you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
    $endgroup$
    – Nick
    Sep 2 '18 at 19:43






  • 1




    $begingroup$
    Made a very simple Sage program to find them.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:01






  • 3




    $begingroup$
    Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:07


















  • $begingroup$
    Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:12






  • 1




    $begingroup$
    As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
    $endgroup$
    – Daniel Fischer
    Sep 2 '18 at 19:23










  • $begingroup$
    you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
    $endgroup$
    – Nick
    Sep 2 '18 at 19:43






  • 1




    $begingroup$
    Made a very simple Sage program to find them.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:01






  • 3




    $begingroup$
    Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
    $endgroup$
    – Yong Hao Ng
    Sep 3 '18 at 5:07
















$begingroup$
Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
$endgroup$
– Daniel Fischer
Sep 2 '18 at 19:12




$begingroup$
Hmm, happens more often after $100$. $p_1 in {101, 107, 137}$ for example.
$endgroup$
– Daniel Fischer
Sep 2 '18 at 19:12




1




1




$begingroup$
As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
$endgroup$
– Daniel Fischer
Sep 2 '18 at 19:23




$begingroup$
As long as you only want to go up to a moderate limit, modify a Sieve of Eratosthenes to record a prime factor of each number (the smallest or the largest would be natural choices). That way, you get the factorisation of every number very cheaply, and with the prime factorisation it's easy to find the factors closest to the square root. If you want to look at large numbers, it won't be so easy. Factoring in general is hard.
$endgroup$
– Daniel Fischer
Sep 2 '18 at 19:23












$begingroup$
you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
$endgroup$
– Nick
Sep 2 '18 at 19:43




$begingroup$
you can use this construct an artificial number system where this is true, then you will find even there it will not hold. try.
$endgroup$
– Nick
Sep 2 '18 at 19:43




1




1




$begingroup$
Made a very simple Sage program to find them.
$endgroup$
– Yong Hao Ng
Sep 3 '18 at 5:01




$begingroup$
Made a very simple Sage program to find them.
$endgroup$
– Yong Hao Ng
Sep 3 '18 at 5:01




3




3




$begingroup$
Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
$endgroup$
– Yong Hao Ng
Sep 3 '18 at 5:07




$begingroup$
Hopefully I didn't make any mistakes. It can handle up to $10^7$ easily, after which it's quite slow. At $10^7$ it fetches $31939$ passes out of $58980$ twin primes which is about 50%. It fetches a similar ratio for $10^3,10^4,cdots,10^7$.
$endgroup$
– Yong Hao Ng
Sep 3 '18 at 5:07










1 Answer
1






active

oldest

votes


















0












$begingroup$

Twin primes other than $3,5$ are of the form $6kpm1$, which makes $p_1-1 = 6k-2$, $p_2 + 1 = 6k+2$, and $p_1+1 = p_2-1 = 6k$. Define $f(x) = min{|a-b|}$ where $a b = x$, and you are asking are there infinitely many $k$ where $6kpm1$ are both primes, and $f(6k-2) < f(6k)$ or $f(6k+2) < f(6k)$.



Experimentally, about $54%$ of the twin primes are "close", not the $33frac13%$ that one would naively expect. Still, most likely infinitely many.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    For what batch size is twin prime closeness avereged at 54%?
    $endgroup$
    – Nick
    Sep 29 '18 at 1:45










  • $begingroup$
    Should this be posted as a comment?
    $endgroup$
    – TheSimpliFire
    Dec 16 '18 at 15:11











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1 Answer
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0












$begingroup$

Twin primes other than $3,5$ are of the form $6kpm1$, which makes $p_1-1 = 6k-2$, $p_2 + 1 = 6k+2$, and $p_1+1 = p_2-1 = 6k$. Define $f(x) = min{|a-b|}$ where $a b = x$, and you are asking are there infinitely many $k$ where $6kpm1$ are both primes, and $f(6k-2) < f(6k)$ or $f(6k+2) < f(6k)$.



Experimentally, about $54%$ of the twin primes are "close", not the $33frac13%$ that one would naively expect. Still, most likely infinitely many.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    For what batch size is twin prime closeness avereged at 54%?
    $endgroup$
    – Nick
    Sep 29 '18 at 1:45










  • $begingroup$
    Should this be posted as a comment?
    $endgroup$
    – TheSimpliFire
    Dec 16 '18 at 15:11
















0












$begingroup$

Twin primes other than $3,5$ are of the form $6kpm1$, which makes $p_1-1 = 6k-2$, $p_2 + 1 = 6k+2$, and $p_1+1 = p_2-1 = 6k$. Define $f(x) = min{|a-b|}$ where $a b = x$, and you are asking are there infinitely many $k$ where $6kpm1$ are both primes, and $f(6k-2) < f(6k)$ or $f(6k+2) < f(6k)$.



Experimentally, about $54%$ of the twin primes are "close", not the $33frac13%$ that one would naively expect. Still, most likely infinitely many.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    For what batch size is twin prime closeness avereged at 54%?
    $endgroup$
    – Nick
    Sep 29 '18 at 1:45










  • $begingroup$
    Should this be posted as a comment?
    $endgroup$
    – TheSimpliFire
    Dec 16 '18 at 15:11














0












0








0





$begingroup$

Twin primes other than $3,5$ are of the form $6kpm1$, which makes $p_1-1 = 6k-2$, $p_2 + 1 = 6k+2$, and $p_1+1 = p_2-1 = 6k$. Define $f(x) = min{|a-b|}$ where $a b = x$, and you are asking are there infinitely many $k$ where $6kpm1$ are both primes, and $f(6k-2) < f(6k)$ or $f(6k+2) < f(6k)$.



Experimentally, about $54%$ of the twin primes are "close", not the $33frac13%$ that one would naively expect. Still, most likely infinitely many.






share|cite|improve this answer











$endgroup$



Twin primes other than $3,5$ are of the form $6kpm1$, which makes $p_1-1 = 6k-2$, $p_2 + 1 = 6k+2$, and $p_1+1 = p_2-1 = 6k$. Define $f(x) = min{|a-b|}$ where $a b = x$, and you are asking are there infinitely many $k$ where $6kpm1$ are both primes, and $f(6k-2) < f(6k)$ or $f(6k+2) < f(6k)$.



Experimentally, about $54%$ of the twin primes are "close", not the $33frac13%$ that one would naively expect. Still, most likely infinitely many.







share|cite|improve this answer














share|cite|improve this answer



share|cite|improve this answer








edited Sep 9 '18 at 10:39









TheSimpliFire

12.5k62460




12.5k62460










answered Sep 3 '18 at 21:39









gnasher729gnasher729

5,9871028




5,9871028












  • $begingroup$
    For what batch size is twin prime closeness avereged at 54%?
    $endgroup$
    – Nick
    Sep 29 '18 at 1:45










  • $begingroup$
    Should this be posted as a comment?
    $endgroup$
    – TheSimpliFire
    Dec 16 '18 at 15:11


















  • $begingroup$
    For what batch size is twin prime closeness avereged at 54%?
    $endgroup$
    – Nick
    Sep 29 '18 at 1:45










  • $begingroup$
    Should this be posted as a comment?
    $endgroup$
    – TheSimpliFire
    Dec 16 '18 at 15:11
















$begingroup$
For what batch size is twin prime closeness avereged at 54%?
$endgroup$
– Nick
Sep 29 '18 at 1:45




$begingroup$
For what batch size is twin prime closeness avereged at 54%?
$endgroup$
– Nick
Sep 29 '18 at 1:45












$begingroup$
Should this be posted as a comment?
$endgroup$
– TheSimpliFire
Dec 16 '18 at 15:11




$begingroup$
Should this be posted as a comment?
$endgroup$
– TheSimpliFire
Dec 16 '18 at 15:11


















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