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Sum of series (1-x^4)^n/(n+2)



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The solution

You have entered [src]
  oo           
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\   `          
 \            n
  \   /     4\ 
   )  \1 - x / 
  /   ---------
 /      n + 2  
/___,          
n = 1          
$$\sum_{n=1}^{\infty} \frac{\left(1 - x^{4}\right)^{n}}{n + 2}$$
Sum((1 - x^4)^n/(n + 2), (n, 1, oo))
The answer [src]
/                           /               /     2\                                                \                                                          
|                           |     3*(1 + x)*\1 + x /*(-1 + x)                                       |                                                          
|                           |-3 + ---------------------------        /            /     2\         \|                                                          
|         /     2\          |                  2                3*log\1 + (1 + x)*\1 + x /*(-1 + x)/|                                                          
|-(1 + x)*\1 + x /*(-1 + x)*|-------------------------------- + ------------------------------------|                                                          
|                           |                   2                                    3              |                                                          
|                           |         2 /     2\          2                3 /     2\          3    |                                                          
|                           \  (1 + x) *\1 + x / *(-1 + x)          (1 + x) *\1 + x / *(-1 + x)     /         /   /     4 ___       \     /      4 ___       \\
|-----------------------------------------------------------------------------------------------------  for Or\And\x <= \/ 2 , x > 0/, And\x >= -\/ 2 , x < 0//
|                                                  3                                                                                                           
<                                                                                                                                                              
|                                             oo                                                                                                               
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|                                           \   `                                                                                                              
|                                            \            n                                                                                                    
|                                             \   /     4\                                                                                                     
|                                              )  \1 - x /                                                                     otherwise                       
|                                             /   ---------                                                                                                    
|                                            /      2 + n                                                                                                      
|                                           /___,                                                                                                              
\                                           n = 1                                                                                                              
$$\begin{cases} - \frac{\left(x - 1\right) \left(x + 1\right) \left(x^{2} + 1\right) \left(\frac{\frac{3 \left(x - 1\right) \left(x + 1\right) \left(x^{2} + 1\right)}{2} - 3}{\left(x - 1\right)^{2} \left(x + 1\right)^{2} \left(x^{2} + 1\right)^{2}} + \frac{3 \log{\left(\left(x - 1\right) \left(x + 1\right) \left(x^{2} + 1\right) + 1 \right)}}{\left(x - 1\right)^{3} \left(x + 1\right)^{3} \left(x^{2} + 1\right)^{3}}\right)}{3} & \text{for}\: \left(x \leq \sqrt[4]{2} \wedge x > 0\right) \vee \left(x \geq - \sqrt[4]{2} \wedge x < 0\right) \\\sum_{n=1}^{\infty} \frac{\left(1 - x^{4}\right)^{n}}{n + 2} & \text{otherwise} \end{cases}$$
Piecewise((-(1 + x)*(1 + x^2)*(-1 + x)*((-3 + 3*(1 + x)*(1 + x^2)*(-1 + x)/2)/((1 + x)^2*(1 + x^2)^2*(-1 + x)^2) + 3*log(1 + (1 + x)*(1 + x^2)*(-1 + x))/((1 + x)^3*(1 + x^2)^3*(-1 + x)^3))/3, ((x > 0)∧(x <= 2^(1/4)))∨((x < 0)∧(x >= -2^(1/4)))), (Sum((1 - x^4)^n/(2 + n), (n, 1, oo)), True))

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