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1/(n*lnn)

Sum of series 1/(n*lnn)



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The solution

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  oo          
 ___          
 \  `         
  \      1    
   )  --------
  /   n*log(n)
 /__,         
n = 2         
$$\sum_{n=2}^{\infty} \frac{1}{n \log{\left(n \right)}}$$
Sum(1/(n*log(n)), (n, 2, oo))
The radius of convergence of the power series
Given number:
$$\frac{1}{n \log{\left(n \right)}}$$
It is a series of species
$$a_{n} \left(c x - x_{0}\right)^{d n}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{n \to \infty} \left|{\frac{a_{n}}{a_{n + 1}}}\right|}{c}$$
In this case
$$a_{n} = \frac{1}{n \log{\left(n \right)}}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left(n + 1\right) \log{\left(n + 1 \right)} \left|{\frac{1}{\log{\left(n \right)}}}\right|}{n}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
The graph
Sum of series 1/(n*lnn)

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