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Sum of series 1/(n2)(2n-1)



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The solution

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  oo         
 ___         
 \  `        
  \   2*n - 1
   )  -------
  /      n2  
 /__,        
n = 1        
$$\sum_{n=1}^{\infty} \frac{2 n - 1}{n_{2}}$$
Sum((2*n - 1)/n2, (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{2 n - 1}{n_{2}}$$
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
$$a_{n} = \frac{2 n - 1}{n_{2}}$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{\left|{2 n - 1}\right|}{2 n + 1}\right)$$
Let's take the limit
we find
True

False
The answer [src]
oo
--
n2
$$\frac{\infty}{n_{2}}$$
oo/n2

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