I thought of utilizing this lockdown period to study research papers in number theory by myself. 

I began reading the research paper By T Estermann ->" On Goldbach Problem :  Proof that Almost all Even Positive Integers are sum of two primes". I have read and understood all the proof except one equation and that too due to reason that it uses a equation as a reference from German Book " E Landau, Vorlesungen über Zahlentheorie I ( Liepzig, 1927) . I don't understand German. 

>I thought of posting this question here in hope that someone must have studied this research paper and also in case a researcher understanding German language wishes to help. 


Image of the equation I don't understand ( equation 49 on Page 7 ) [! Equation 49][1]][1]

> The problem-> 1.I am unable to understand  what ( 2|m)  means in (49) ?(Notation (2|m) is not used in research paper before) 2.what is the statement of theorem is used to derive (49)? . . Everything except this theorem is Understood in paper. 

Images from Original German book->[![Image page 226 ][2]][2][![Image pg 227][3]][3]

> What i did to resolve the issue -> I tried to find English Edition but couldn't. 2.Then I tried to translate  whole pdf book  which didn't materalized due to book being a bit long. 3.When I split the pdf I wanted to translate theb it Shows Error 403.
4. I changed the screenshot images( from archive.org) to pdf but again error in translation. 

> It is my humble request if anybody can tell me meaning of notation (2|m) ? 

And it will be very much more helpful if someone tell what is the statement of theorem / result used to derive equation 49.

> I shall be really thankful for any help offered. 





  [1]: https://i.sstatic.net/xZLTM.jpg
  [2]: https://i.sstatic.net/mc6VY.jpg
  [3]: https://i.sstatic.net/skziU.jpg