Integral de -x^2sin(nx) dx

                           //                  0                     for n = 0\                              
                           ||                                                 |                              
                           || //cos(n*x)   x*sin(n*x)            \            |                              
  /                        || ||-------- + ----------  for n != 0|            |                              
 |                         || ||    2          n                 |            |      //    0       for n = 0\
 |   2                     || ||   n                             |            |    2 ||                     |
 | -x *sin(n*x) dx = C + 2*|<-|<                                 |            | - x *|<-cos(n*x)            |
 |                         || ||          2                      |            |      ||----------  otherwise|
/                          || ||         x                       |            |      \\    n                /
                           || ||         --            otherwise |            |                              
                           || \\         2                       /            |                              
                           ||--------------------------------------  otherwise|                              
                           \\                  n                              /                              

$$\int - x^{2} \sin{\left(n x \right)}\, dx = C - x^{2} \left(\begin{cases} 0 & \text{for}\: n = 0 \\- \frac{\cos{\left(n x \right)}}{n} & \text{otherwise} \end{cases}\right) + 2 \left(\begin{cases} 0 & \text{for}\: n = 0 \\- \frac{\begin{cases} \frac{x \sin{\left(n x \right)}}{n} + \frac{\cos{\left(n x \right)}}{n^{2}} & \text{for}\: n \neq 0 \\\frac{x^{2}}{2} & \text{otherwise} \end{cases}}{n} & \text{otherwise} \end{cases}\right)$$

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