Who derived this equation? [number theory]

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Does anyone know the name of the paper in which this equation first appeared? Thank you!
$$int_0^infty e^-nxx^s-1dx = Pi(s-1)/n^s$$







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    Does anyone know the name of the paper in which this equation first appeared? Thank you!
    $$int_0^infty e^-nxx^s-1dx = Pi(s-1)/n^s$$







    share|cite|improve this question























      up vote
      2
      down vote

      favorite
      1









      up vote
      2
      down vote

      favorite
      1






      1





      Does anyone know the name of the paper in which this equation first appeared? Thank you!
      $$int_0^infty e^-nxx^s-1dx = Pi(s-1)/n^s$$







      share|cite|improve this question













      Does anyone know the name of the paper in which this equation first appeared? Thank you!
      $$int_0^infty e^-nxx^s-1dx = Pi(s-1)/n^s$$









      share|cite|improve this question












      share|cite|improve this question




      share|cite|improve this question








      edited Jul 31 at 13:44









      joriki

      164k10179328




      164k10179328









      asked Jul 31 at 13:36









      Christina Daniel

      132




      132




















          3 Answers
          3






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          up vote
          1
          down vote



          accepted










          It was (almost certainly) Euler. For example, we find it in E675, De valoribus integralium a termino variabilis $x=0$ usque ad $x=infty$ extensorum (1781). A translation of this paper may be found on arXiv. At the bottom of p. 3 of the translation one finds




          §8. I first put $x=ky$, and because both terms of the integral stay the same, it will be
          $$k^n int y^n−1partial y cdot e^−ky= Delta, $$
          where this formula is also extended from $y= 0$ up to $y=infty$; then dividing this by $k^n$ we will have
          $$ int y^n−1partial y cdot e^−ky=fracDeltak^n $$,where it should however be noted that no negative numbers can be taken for $k$, as otherwise the formula $e^−ky$ would no longer vanish in the case $y=infty$;and these are the only values which ought to be excluded here, so that even imaginary values could be used in place of $k$, and then I pursued these laborious integrations.




          (And yes, Euler does consider non-integer $n$ in the paper: he discusses $n=1/2$ later on.)






          share|cite|improve this answer





















          • Thank you so much!
            – Christina Daniel
            Jul 31 at 14:31

















          up vote
          2
          down vote













          That formula is easily seen to be equivalent to the integral definition of the Gamma function, introduced by Euler in a letter to Goldbach in 1730. (Note that $Pi(s-1)=Gamma(s)$.)



          Source: Wikipedia.






          share|cite|improve this answer




























            up vote
            0
            down vote













            I suppose that it was in Riemann's On the number of primes less than a given magnitude. It's the second formula that appears there.






            share|cite|improve this answer





















            • If the question is really about the formula exactly as presented, I suppose you win. ;-)
              – Harald Hanche-Olsen
              Jul 31 at 13:49










            • Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
              – Christina Daniel
              Jul 31 at 13:54







            • 1




              Hey! It's Riemann that we're talking about. Of course it was obvious to him.
              – José Carlos Santos
              Jul 31 at 14:00










            • But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
              – Christina Daniel
              Jul 31 at 14:12






            • 1




              It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
              – Harald Hanche-Olsen
              Jul 31 at 14:13











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            3 Answers
            3






            active

            oldest

            votes








            3 Answers
            3






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            It was (almost certainly) Euler. For example, we find it in E675, De valoribus integralium a termino variabilis $x=0$ usque ad $x=infty$ extensorum (1781). A translation of this paper may be found on arXiv. At the bottom of p. 3 of the translation one finds




            §8. I first put $x=ky$, and because both terms of the integral stay the same, it will be
            $$k^n int y^n−1partial y cdot e^−ky= Delta, $$
            where this formula is also extended from $y= 0$ up to $y=infty$; then dividing this by $k^n$ we will have
            $$ int y^n−1partial y cdot e^−ky=fracDeltak^n $$,where it should however be noted that no negative numbers can be taken for $k$, as otherwise the formula $e^−ky$ would no longer vanish in the case $y=infty$;and these are the only values which ought to be excluded here, so that even imaginary values could be used in place of $k$, and then I pursued these laborious integrations.




            (And yes, Euler does consider non-integer $n$ in the paper: he discusses $n=1/2$ later on.)






            share|cite|improve this answer





















            • Thank you so much!
              – Christina Daniel
              Jul 31 at 14:31














            up vote
            1
            down vote



            accepted










            It was (almost certainly) Euler. For example, we find it in E675, De valoribus integralium a termino variabilis $x=0$ usque ad $x=infty$ extensorum (1781). A translation of this paper may be found on arXiv. At the bottom of p. 3 of the translation one finds




            §8. I first put $x=ky$, and because both terms of the integral stay the same, it will be
            $$k^n int y^n−1partial y cdot e^−ky= Delta, $$
            where this formula is also extended from $y= 0$ up to $y=infty$; then dividing this by $k^n$ we will have
            $$ int y^n−1partial y cdot e^−ky=fracDeltak^n $$,where it should however be noted that no negative numbers can be taken for $k$, as otherwise the formula $e^−ky$ would no longer vanish in the case $y=infty$;and these are the only values which ought to be excluded here, so that even imaginary values could be used in place of $k$, and then I pursued these laborious integrations.




            (And yes, Euler does consider non-integer $n$ in the paper: he discusses $n=1/2$ later on.)






            share|cite|improve this answer





















            • Thank you so much!
              – Christina Daniel
              Jul 31 at 14:31












            up vote
            1
            down vote



            accepted







            up vote
            1
            down vote



            accepted






            It was (almost certainly) Euler. For example, we find it in E675, De valoribus integralium a termino variabilis $x=0$ usque ad $x=infty$ extensorum (1781). A translation of this paper may be found on arXiv. At the bottom of p. 3 of the translation one finds




            §8. I first put $x=ky$, and because both terms of the integral stay the same, it will be
            $$k^n int y^n−1partial y cdot e^−ky= Delta, $$
            where this formula is also extended from $y= 0$ up to $y=infty$; then dividing this by $k^n$ we will have
            $$ int y^n−1partial y cdot e^−ky=fracDeltak^n $$,where it should however be noted that no negative numbers can be taken for $k$, as otherwise the formula $e^−ky$ would no longer vanish in the case $y=infty$;and these are the only values which ought to be excluded here, so that even imaginary values could be used in place of $k$, and then I pursued these laborious integrations.




            (And yes, Euler does consider non-integer $n$ in the paper: he discusses $n=1/2$ later on.)






            share|cite|improve this answer













            It was (almost certainly) Euler. For example, we find it in E675, De valoribus integralium a termino variabilis $x=0$ usque ad $x=infty$ extensorum (1781). A translation of this paper may be found on arXiv. At the bottom of p. 3 of the translation one finds




            §8. I first put $x=ky$, and because both terms of the integral stay the same, it will be
            $$k^n int y^n−1partial y cdot e^−ky= Delta, $$
            where this formula is also extended from $y= 0$ up to $y=infty$; then dividing this by $k^n$ we will have
            $$ int y^n−1partial y cdot e^−ky=fracDeltak^n $$,where it should however be noted that no negative numbers can be taken for $k$, as otherwise the formula $e^−ky$ would no longer vanish in the case $y=infty$;and these are the only values which ought to be excluded here, so that even imaginary values could be used in place of $k$, and then I pursued these laborious integrations.




            (And yes, Euler does consider non-integer $n$ in the paper: he discusses $n=1/2$ later on.)







            share|cite|improve this answer













            share|cite|improve this answer



            share|cite|improve this answer











            answered Jul 31 at 14:15









            Chappers

            54.9k74190




            54.9k74190











            • Thank you so much!
              – Christina Daniel
              Jul 31 at 14:31
















            • Thank you so much!
              – Christina Daniel
              Jul 31 at 14:31















            Thank you so much!
            – Christina Daniel
            Jul 31 at 14:31




            Thank you so much!
            – Christina Daniel
            Jul 31 at 14:31










            up vote
            2
            down vote













            That formula is easily seen to be equivalent to the integral definition of the Gamma function, introduced by Euler in a letter to Goldbach in 1730. (Note that $Pi(s-1)=Gamma(s)$.)



            Source: Wikipedia.






            share|cite|improve this answer

























              up vote
              2
              down vote













              That formula is easily seen to be equivalent to the integral definition of the Gamma function, introduced by Euler in a letter to Goldbach in 1730. (Note that $Pi(s-1)=Gamma(s)$.)



              Source: Wikipedia.






              share|cite|improve this answer























                up vote
                2
                down vote










                up vote
                2
                down vote









                That formula is easily seen to be equivalent to the integral definition of the Gamma function, introduced by Euler in a letter to Goldbach in 1730. (Note that $Pi(s-1)=Gamma(s)$.)



                Source: Wikipedia.






                share|cite|improve this answer













                That formula is easily seen to be equivalent to the integral definition of the Gamma function, introduced by Euler in a letter to Goldbach in 1730. (Note that $Pi(s-1)=Gamma(s)$.)



                Source: Wikipedia.







                share|cite|improve this answer













                share|cite|improve this answer



                share|cite|improve this answer











                answered Jul 31 at 13:46









                Harald Hanche-Olsen

                27.3k23959




                27.3k23959




















                    up vote
                    0
                    down vote













                    I suppose that it was in Riemann's On the number of primes less than a given magnitude. It's the second formula that appears there.






                    share|cite|improve this answer





















                    • If the question is really about the formula exactly as presented, I suppose you win. ;-)
                      – Harald Hanche-Olsen
                      Jul 31 at 13:49










                    • Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                      – Christina Daniel
                      Jul 31 at 13:54







                    • 1




                      Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                      – José Carlos Santos
                      Jul 31 at 14:00










                    • But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                      – Christina Daniel
                      Jul 31 at 14:12






                    • 1




                      It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                      – Harald Hanche-Olsen
                      Jul 31 at 14:13















                    up vote
                    0
                    down vote













                    I suppose that it was in Riemann's On the number of primes less than a given magnitude. It's the second formula that appears there.






                    share|cite|improve this answer





















                    • If the question is really about the formula exactly as presented, I suppose you win. ;-)
                      – Harald Hanche-Olsen
                      Jul 31 at 13:49










                    • Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                      – Christina Daniel
                      Jul 31 at 13:54







                    • 1




                      Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                      – José Carlos Santos
                      Jul 31 at 14:00










                    • But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                      – Christina Daniel
                      Jul 31 at 14:12






                    • 1




                      It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                      – Harald Hanche-Olsen
                      Jul 31 at 14:13













                    up vote
                    0
                    down vote










                    up vote
                    0
                    down vote









                    I suppose that it was in Riemann's On the number of primes less than a given magnitude. It's the second formula that appears there.






                    share|cite|improve this answer













                    I suppose that it was in Riemann's On the number of primes less than a given magnitude. It's the second formula that appears there.







                    share|cite|improve this answer













                    share|cite|improve this answer



                    share|cite|improve this answer











                    answered Jul 31 at 13:47









                    José Carlos Santos

                    112k1696172




                    112k1696172











                    • If the question is really about the formula exactly as presented, I suppose you win. ;-)
                      – Harald Hanche-Olsen
                      Jul 31 at 13:49










                    • Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                      – Christina Daniel
                      Jul 31 at 13:54







                    • 1




                      Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                      – José Carlos Santos
                      Jul 31 at 14:00










                    • But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                      – Christina Daniel
                      Jul 31 at 14:12






                    • 1




                      It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                      – Harald Hanche-Olsen
                      Jul 31 at 14:13

















                    • If the question is really about the formula exactly as presented, I suppose you win. ;-)
                      – Harald Hanche-Olsen
                      Jul 31 at 13:49










                    • Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                      – Christina Daniel
                      Jul 31 at 13:54







                    • 1




                      Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                      – José Carlos Santos
                      Jul 31 at 14:00










                    • But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                      – Christina Daniel
                      Jul 31 at 14:12






                    • 1




                      It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                      – Harald Hanche-Olsen
                      Jul 31 at 14:13
















                    If the question is really about the formula exactly as presented, I suppose you win. ;-)
                    – Harald Hanche-Olsen
                    Jul 31 at 13:49




                    If the question is really about the formula exactly as presented, I suppose you win. ;-)
                    – Harald Hanche-Olsen
                    Jul 31 at 13:49












                    Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                    – Christina Daniel
                    Jul 31 at 13:54





                    Yes. So Riemann writes "on making use of the equation" as if the equation is already established, so I am wondering where it came from, or if it is "obvious."
                    – Christina Daniel
                    Jul 31 at 13:54





                    1




                    1




                    Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                    – José Carlos Santos
                    Jul 31 at 14:00




                    Hey! It's Riemann that we're talking about. Of course it was obvious to him.
                    – José Carlos Santos
                    Jul 31 at 14:00












                    But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                    – Christina Daniel
                    Jul 31 at 14:12




                    But the rest of the paper is more pedagogical... the difference in flow doesn't make sense!
                    – Christina Daniel
                    Jul 31 at 14:12




                    1




                    1




                    It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                    – Harald Hanche-Olsen
                    Jul 31 at 14:13





                    It's “obvious” in the sense that it only requires substituting $x=t/n$ in the integral. To Riemann, and most likely to his intended audience, that is no great stretch.
                    – Harald Hanche-Olsen
                    Jul 31 at 14:13













                     

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