Is it possible to find 2014 distinct positive integers whose sum is divisible by each of them?












1












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Is it possible to find 2014 distinct positive integers whose sum is divisible by each of them?

I'm not really sure how to even approach this question.

Source: Washington's Monthly Math Hour, 2014










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Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • $begingroup$
    I cant even find two.
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago






  • 1




    $begingroup$
    @Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
    $endgroup$
    – JMoravitz
    2 hours ago










  • $begingroup$
    Well, at least I can find three… $1+2+3$
    $endgroup$
    – Wolfgang Kais
    2 hours ago










  • $begingroup$
    @JMoravitz humor?
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago
















1












$begingroup$


Is it possible to find 2014 distinct positive integers whose sum is divisible by each of them?

I'm not really sure how to even approach this question.

Source: Washington's Monthly Math Hour, 2014










share|cite|improve this question







New contributor




Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$












  • $begingroup$
    I cant even find two.
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago






  • 1




    $begingroup$
    @Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
    $endgroup$
    – JMoravitz
    2 hours ago










  • $begingroup$
    Well, at least I can find three… $1+2+3$
    $endgroup$
    – Wolfgang Kais
    2 hours ago










  • $begingroup$
    @JMoravitz humor?
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago














1












1








1





$begingroup$


Is it possible to find 2014 distinct positive integers whose sum is divisible by each of them?

I'm not really sure how to even approach this question.

Source: Washington's Monthly Math Hour, 2014










share|cite|improve this question







New contributor




Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




Is it possible to find 2014 distinct positive integers whose sum is divisible by each of them?

I'm not really sure how to even approach this question.

Source: Washington's Monthly Math Hour, 2014







discrete-mathematics intuition pigeonhole-principle






share|cite|improve this question







New contributor




Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question







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Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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asked 2 hours ago









Arvin DingArvin Ding

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84




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New contributor





Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Arvin Ding is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • $begingroup$
    I cant even find two.
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago






  • 1




    $begingroup$
    @Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
    $endgroup$
    – JMoravitz
    2 hours ago










  • $begingroup$
    Well, at least I can find three… $1+2+3$
    $endgroup$
    – Wolfgang Kais
    2 hours ago










  • $begingroup$
    @JMoravitz humor?
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago


















  • $begingroup$
    I cant even find two.
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago






  • 1




    $begingroup$
    @Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
    $endgroup$
    – JMoravitz
    2 hours ago










  • $begingroup$
    Well, at least I can find three… $1+2+3$
    $endgroup$
    – Wolfgang Kais
    2 hours ago










  • $begingroup$
    @JMoravitz humor?
    $endgroup$
    – Rudi_Birnbaum
    2 hours ago
















$begingroup$
I cant even find two.
$endgroup$
– Rudi_Birnbaum
2 hours ago




$begingroup$
I cant even find two.
$endgroup$
– Rudi_Birnbaum
2 hours ago




1




1




$begingroup$
@Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
$endgroup$
– JMoravitz
2 hours ago




$begingroup$
@Rudi_Birnbaum irrelevant. $2,4,6,12$ are all divisors of $2+4+6+12$.
$endgroup$
– JMoravitz
2 hours ago












$begingroup$
Well, at least I can find three… $1+2+3$
$endgroup$
– Wolfgang Kais
2 hours ago




$begingroup$
Well, at least I can find three… $1+2+3$
$endgroup$
– Wolfgang Kais
2 hours ago












$begingroup$
@JMoravitz humor?
$endgroup$
– Rudi_Birnbaum
2 hours ago




$begingroup$
@JMoravitz humor?
$endgroup$
– Rudi_Birnbaum
2 hours ago










2 Answers
2






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5












$begingroup$

Hint: $2,4,6$ are all divisors of $2+4+6=12$. Similarly $2+4+6+12$ are all divisors of $2+4+6+12=24$




So too are $2,4,6,12,24$ all divisors of $2+4+6+12+24$




$~$




Claim: Let $x_1=2, x_2=4, x_3=6$ and let $x_{n+1} = sumlimits_{k=1}^n x_k$ for each $ngeq 3$. You have that $x_imid sumlimits_{k=1}^nx_k$ for all $ileq n$ for all $ngeq 3$.







share|cite|improve this answer









$endgroup$





















    5












    $begingroup$

    $$begin{align}
    1+2+3&=6\
    1+2+3+6&=12\
    1+2+3+6+12&=24\
    vdots
    end{align}$$






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
      $endgroup$
      – Ross Millikan
      2 hours ago













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    2 Answers
    2






    active

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    2 Answers
    2






    active

    oldest

    votes









    active

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    active

    oldest

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    5












    $begingroup$

    Hint: $2,4,6$ are all divisors of $2+4+6=12$. Similarly $2+4+6+12$ are all divisors of $2+4+6+12=24$




    So too are $2,4,6,12,24$ all divisors of $2+4+6+12+24$




    $~$




    Claim: Let $x_1=2, x_2=4, x_3=6$ and let $x_{n+1} = sumlimits_{k=1}^n x_k$ for each $ngeq 3$. You have that $x_imid sumlimits_{k=1}^nx_k$ for all $ileq n$ for all $ngeq 3$.







    share|cite|improve this answer









    $endgroup$


















      5












      $begingroup$

      Hint: $2,4,6$ are all divisors of $2+4+6=12$. Similarly $2+4+6+12$ are all divisors of $2+4+6+12=24$




      So too are $2,4,6,12,24$ all divisors of $2+4+6+12+24$




      $~$




      Claim: Let $x_1=2, x_2=4, x_3=6$ and let $x_{n+1} = sumlimits_{k=1}^n x_k$ for each $ngeq 3$. You have that $x_imid sumlimits_{k=1}^nx_k$ for all $ileq n$ for all $ngeq 3$.







      share|cite|improve this answer









      $endgroup$
















        5












        5








        5





        $begingroup$

        Hint: $2,4,6$ are all divisors of $2+4+6=12$. Similarly $2+4+6+12$ are all divisors of $2+4+6+12=24$




        So too are $2,4,6,12,24$ all divisors of $2+4+6+12+24$




        $~$




        Claim: Let $x_1=2, x_2=4, x_3=6$ and let $x_{n+1} = sumlimits_{k=1}^n x_k$ for each $ngeq 3$. You have that $x_imid sumlimits_{k=1}^nx_k$ for all $ileq n$ for all $ngeq 3$.







        share|cite|improve this answer









        $endgroup$



        Hint: $2,4,6$ are all divisors of $2+4+6=12$. Similarly $2+4+6+12$ are all divisors of $2+4+6+12=24$




        So too are $2,4,6,12,24$ all divisors of $2+4+6+12+24$




        $~$




        Claim: Let $x_1=2, x_2=4, x_3=6$ and let $x_{n+1} = sumlimits_{k=1}^n x_k$ for each $ngeq 3$. You have that $x_imid sumlimits_{k=1}^nx_k$ for all $ileq n$ for all $ngeq 3$.








        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered 2 hours ago









        JMoravitzJMoravitz

        48.2k33886




        48.2k33886























            5












            $begingroup$

            $$begin{align}
            1+2+3&=6\
            1+2+3+6&=12\
            1+2+3+6+12&=24\
            vdots
            end{align}$$






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
              $endgroup$
              – Ross Millikan
              2 hours ago


















            5












            $begingroup$

            $$begin{align}
            1+2+3&=6\
            1+2+3+6&=12\
            1+2+3+6+12&=24\
            vdots
            end{align}$$






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
              $endgroup$
              – Ross Millikan
              2 hours ago
















            5












            5








            5





            $begingroup$

            $$begin{align}
            1+2+3&=6\
            1+2+3+6&=12\
            1+2+3+6+12&=24\
            vdots
            end{align}$$






            share|cite|improve this answer









            $endgroup$



            $$begin{align}
            1+2+3&=6\
            1+2+3+6&=12\
            1+2+3+6+12&=24\
            vdots
            end{align}$$







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered 2 hours ago









            saulspatzsaulspatz

            17k31434




            17k31434












            • $begingroup$
              We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
              $endgroup$
              – Ross Millikan
              2 hours ago




















            • $begingroup$
              We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
              $endgroup$
              – Ross Millikan
              2 hours ago


















            $begingroup$
            We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
            $endgroup$
            – Ross Millikan
            2 hours ago






            $begingroup$
            We can say that the $2014$ numbers produced this way are $1,2,3$ and $3cdot 2^k$ for $k in [1,2011]$
            $endgroup$
            – Ross Millikan
            2 hours ago












            Arvin Ding is a new contributor. Be nice, and check out our Code of Conduct.










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