Prove that the series SUM (-1)^n n/p_n converges where p_n are primes

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SUMMARY

The series \(\sum (-1)^n \frac{n}{p_n}\), where \(p_n\) represents the nth prime, converges under specific conditions. The discussion highlights that the sequence \(\frac{n}{p_n}\) is not monotonic, particularly if there are infinitely many twin primes, which complicates the application of the alternating series test. The prime number theorem indicates that \(\lim_{n \rightarrow \infty} \frac{p_n}{n \ln n} = 1\), suggesting that while \(n/p_n\) approaches 0, this alone is insufficient to confirm convergence without additional assumptions, such as the twin prime conjecture.

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  • Understanding of alternating series and convergence tests
  • Familiarity with prime number theory and the prime number theorem
  • Knowledge of the twin prime conjecture
  • Basic calculus concepts related to limits and sequences
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  • Research the implications of the twin prime conjecture on series convergence
  • Study the application of the prime number theorem in series analysis
  • Explore advanced convergence tests beyond the alternating series test
  • Investigate the behavior of \(\frac{n}{p_n}\) for large \(n\) in detail
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Homework Statement



Prove that \sum(-1)^n\frac{n}{p_n} converges, where p_n is the nth prime.

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The sequence \frac{n}{p_n} is definitely not monotone if there exists infinitely many twin primes, since 2n-p_n<0 for sufficiently large n, so alternating series test is out. Are there any other ways of showing this converges?
 
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Can you use the prime number theorem? This says that:

\lim_{n \rightarrow \infty} \frac{p_n}{n \ln n} = 1
 
I can't use it for the series. I can only establish that n/p_n -> 0, which is insufficient for the series. I can't even prove that n/p_n is NOT monotone for large n, unless I assume the twin prime conjecture, for example.
 

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