Do These Mathematical Series Converge?

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SUMMARY

The discussion focuses on the convergence of two mathematical series: the first series, {\sum\limits_{n = 1}^\infty {\left[ {\left( {\sum\limits_{k = 1}^n {\frac{1}{k}} } \right)^{ - 1} } \right]} }, diverges, while the second series, {\sum\limits_{n = 1}^\infty {\left[ {\left( {\sum\limits_{k = 1}^n {k!} } \right)^{ - 1} } \right]} }, converges. The divergence of the first series is established through bounding the internal sum using the harmonic series, while the convergence of the second series is supported by the properties of exponential growth in factorials.

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bomba923
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(This isn't homework :redface:)

Does this series converge?
[tex]{\sum\limits_{n = 1}^\infty {\left[ {\left( {\sum\limits_{k = 1}^n {\frac{1}{k}} } \right)^{ - 1} } \right]} }[/tex]

Does this series converge?
[tex]{\sum\limits_{n = 1}^\infty {\left[ {\left( {\sum\limits_{k = 1}^n {k!} } \right)^{ - 1} } \right]} }[/tex]

**I would appreciate any help
 
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The second one obviously converges, and almost as obviously the first diverges. (I hope...)

Bound the internal sum above by something and below by something in the first and second respectively, so that after inverting you're bounding each term in the big sum below and above. If done correctly you see that the first diverges (hint: think harmonic) and the second converges (think exponential)
 
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