The partial sum and partial product of $zeta$function












4












$begingroup$


Taking the partial sum of the $zeta $ function:



$$zeta^H(s,k)=sum_{n=0}^k frac{1}{n^s}$$



and the partial product f the $zeta $ function:



$$zeta^P(s,j)=prod_{i=0}^j frac{1}{1-p_i^{-s}}$$



I have two questions:



(1) For $p$ being prime and $n,k,iinBbb N$; do there exist closed functions for $zeta^H(s,k)$ and $zeta^P(s,j)$ to which the partial sum respectively the partial product converge?



(2) Does anybody know from a proof that would confirm that for a given $s$, if and if only $j,ktoinfty$ then:
$$zeta^H(s,k)-zeta^P(s,j)to0$$



Thanks for your help in advance.










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$endgroup$












  • $begingroup$
    If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
    $endgroup$
    – i707107
    May 20 '13 at 20:04










  • $begingroup$
    sure, this is trivial. But my questions were about what happens before?
    $endgroup$
    – al-Hwarizmi
    May 21 '13 at 11:45
















4












$begingroup$


Taking the partial sum of the $zeta $ function:



$$zeta^H(s,k)=sum_{n=0}^k frac{1}{n^s}$$



and the partial product f the $zeta $ function:



$$zeta^P(s,j)=prod_{i=0}^j frac{1}{1-p_i^{-s}}$$



I have two questions:



(1) For $p$ being prime and $n,k,iinBbb N$; do there exist closed functions for $zeta^H(s,k)$ and $zeta^P(s,j)$ to which the partial sum respectively the partial product converge?



(2) Does anybody know from a proof that would confirm that for a given $s$, if and if only $j,ktoinfty$ then:
$$zeta^H(s,k)-zeta^P(s,j)to0$$



Thanks for your help in advance.










share|cite|improve this question









$endgroup$












  • $begingroup$
    If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
    $endgroup$
    – i707107
    May 20 '13 at 20:04










  • $begingroup$
    sure, this is trivial. But my questions were about what happens before?
    $endgroup$
    – al-Hwarizmi
    May 21 '13 at 11:45














4












4








4


1



$begingroup$


Taking the partial sum of the $zeta $ function:



$$zeta^H(s,k)=sum_{n=0}^k frac{1}{n^s}$$



and the partial product f the $zeta $ function:



$$zeta^P(s,j)=prod_{i=0}^j frac{1}{1-p_i^{-s}}$$



I have two questions:



(1) For $p$ being prime and $n,k,iinBbb N$; do there exist closed functions for $zeta^H(s,k)$ and $zeta^P(s,j)$ to which the partial sum respectively the partial product converge?



(2) Does anybody know from a proof that would confirm that for a given $s$, if and if only $j,ktoinfty$ then:
$$zeta^H(s,k)-zeta^P(s,j)to0$$



Thanks for your help in advance.










share|cite|improve this question









$endgroup$




Taking the partial sum of the $zeta $ function:



$$zeta^H(s,k)=sum_{n=0}^k frac{1}{n^s}$$



and the partial product f the $zeta $ function:



$$zeta^P(s,j)=prod_{i=0}^j frac{1}{1-p_i^{-s}}$$



I have two questions:



(1) For $p$ being prime and $n,k,iinBbb N$; do there exist closed functions for $zeta^H(s,k)$ and $zeta^P(s,j)$ to which the partial sum respectively the partial product converge?



(2) Does anybody know from a proof that would confirm that for a given $s$, if and if only $j,ktoinfty$ then:
$$zeta^H(s,k)-zeta^P(s,j)to0$$



Thanks for your help in advance.







riemann-zeta euler-product






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asked May 20 '13 at 19:00









al-Hwarizmial-Hwarizmi

2,64511131




2,64511131












  • $begingroup$
    If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
    $endgroup$
    – i707107
    May 20 '13 at 20:04










  • $begingroup$
    sure, this is trivial. But my questions were about what happens before?
    $endgroup$
    – al-Hwarizmi
    May 21 '13 at 11:45


















  • $begingroup$
    If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
    $endgroup$
    – i707107
    May 20 '13 at 20:04










  • $begingroup$
    sure, this is trivial. But my questions were about what happens before?
    $endgroup$
    – al-Hwarizmi
    May 21 '13 at 11:45
















$begingroup$
If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
$endgroup$
– i707107
May 20 '13 at 20:04




$begingroup$
If the real part of $s$ is greater than 1, then both finite product and finite sum converge absolutely to $zeta(s)$.
$endgroup$
– i707107
May 20 '13 at 20:04












$begingroup$
sure, this is trivial. But my questions were about what happens before?
$endgroup$
– al-Hwarizmi
May 21 '13 at 11:45




$begingroup$
sure, this is trivial. But my questions were about what happens before?
$endgroup$
– al-Hwarizmi
May 21 '13 at 11:45










1 Answer
1






active

oldest

votes


















0












$begingroup$

For $s=1$ and positive nonzero integer $k$ you have the harmonic numbers. Their numerators are in the OEIS as sequence A001008 and their denominators as A002805.



That being said, there are other formulas that express your function $zeta^H$. For instance, this paper by Borwein, Fee, Ferguson and Van Der Waall proposes the following (by denoting your function $zeta^H (s,k)$ by $zeta_N(s)=displaystylesum_{n=1}^{N}n^{-s}$):



$$
zeta(s) = zeta_{N-1}(s) +N^{-s} + frac{N^{1-s}}{a-1} + sum_{n=1}^{infty} frac{B_{2n}}{(2n)!}left( prod_{j=0}^{2n-2} (s+j) right) N^{1-s-2n} + R,
$$



where the $B_n$ are the Bernouilli numbers.






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    1 Answer
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    0












    $begingroup$

    For $s=1$ and positive nonzero integer $k$ you have the harmonic numbers. Their numerators are in the OEIS as sequence A001008 and their denominators as A002805.



    That being said, there are other formulas that express your function $zeta^H$. For instance, this paper by Borwein, Fee, Ferguson and Van Der Waall proposes the following (by denoting your function $zeta^H (s,k)$ by $zeta_N(s)=displaystylesum_{n=1}^{N}n^{-s}$):



    $$
    zeta(s) = zeta_{N-1}(s) +N^{-s} + frac{N^{1-s}}{a-1} + sum_{n=1}^{infty} frac{B_{2n}}{(2n)!}left( prod_{j=0}^{2n-2} (s+j) right) N^{1-s-2n} + R,
    $$



    where the $B_n$ are the Bernouilli numbers.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      For $s=1$ and positive nonzero integer $k$ you have the harmonic numbers. Their numerators are in the OEIS as sequence A001008 and their denominators as A002805.



      That being said, there are other formulas that express your function $zeta^H$. For instance, this paper by Borwein, Fee, Ferguson and Van Der Waall proposes the following (by denoting your function $zeta^H (s,k)$ by $zeta_N(s)=displaystylesum_{n=1}^{N}n^{-s}$):



      $$
      zeta(s) = zeta_{N-1}(s) +N^{-s} + frac{N^{1-s}}{a-1} + sum_{n=1}^{infty} frac{B_{2n}}{(2n)!}left( prod_{j=0}^{2n-2} (s+j) right) N^{1-s-2n} + R,
      $$



      where the $B_n$ are the Bernouilli numbers.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        For $s=1$ and positive nonzero integer $k$ you have the harmonic numbers. Their numerators are in the OEIS as sequence A001008 and their denominators as A002805.



        That being said, there are other formulas that express your function $zeta^H$. For instance, this paper by Borwein, Fee, Ferguson and Van Der Waall proposes the following (by denoting your function $zeta^H (s,k)$ by $zeta_N(s)=displaystylesum_{n=1}^{N}n^{-s}$):



        $$
        zeta(s) = zeta_{N-1}(s) +N^{-s} + frac{N^{1-s}}{a-1} + sum_{n=1}^{infty} frac{B_{2n}}{(2n)!}left( prod_{j=0}^{2n-2} (s+j) right) N^{1-s-2n} + R,
        $$



        where the $B_n$ are the Bernouilli numbers.






        share|cite|improve this answer









        $endgroup$



        For $s=1$ and positive nonzero integer $k$ you have the harmonic numbers. Their numerators are in the OEIS as sequence A001008 and their denominators as A002805.



        That being said, there are other formulas that express your function $zeta^H$. For instance, this paper by Borwein, Fee, Ferguson and Van Der Waall proposes the following (by denoting your function $zeta^H (s,k)$ by $zeta_N(s)=displaystylesum_{n=1}^{N}n^{-s}$):



        $$
        zeta(s) = zeta_{N-1}(s) +N^{-s} + frac{N^{1-s}}{a-1} + sum_{n=1}^{infty} frac{B_{2n}}{(2n)!}left( prod_{j=0}^{2n-2} (s+j) right) N^{1-s-2n} + R,
        $$



        where the $B_n$ are the Bernouilli numbers.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 17 '18 at 11:57









        KlangenKlangen

        1,71011334




        1,71011334






























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