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e^n/(1+e^(2*n))

Sum of series e^n/(1+e^(2*n))



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The solution

You have entered [src]
  oo          
____          
\   `         
 \        n   
  \      E    
   )  --------
  /        2*n
 /    1 + E   
/___,         
n = 1         
$$\sum_{n=1}^{\infty} \frac{e^{n}}{e^{2 n} + 1}$$
Sum(E^n/(1 + E^(2*n)), (n, 1, oo))
The radius of convergence of the power series
Given number:
$$\frac{e^{n}}{e^{2 n} + 1}$$
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
$$a_{n} = \frac{1}{e^{2 n} + 1}$$
and
$$x_{0} = - e$$
,
$$d = 1$$
,
$$c = 0$$
then
$$R = \tilde{\infty} \left(- e + \lim_{n \to \infty}\left(\frac{e^{2 n + 2} + 1}{e^{2 n} + 1}\right)\right)$$
Let's take the limit
we find
False

False
The rate of convergence of the power series
The answer [src]
  oo          
____          
\   `         
 \        n   
  \      e    
   )  --------
  /        2*n
 /    1 + e   
/___,         
n = 1         
$$\sum_{n=1}^{\infty} \frac{e^{n}}{e^{2 n} + 1}$$
Sum(exp(n)/(1 + exp(2*n)), (n, 1, oo))
Numerical answer [src]
0.535560664983911584785786496342
0.535560664983911584785786496342
The graph
Sum of series e^n/(1+e^(2*n))

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