The third derivative
[src]
/ 2 \
| 4*x |
2*|-1 + ------|*(2 + sin(x))
| 2|
3*sin(x) 6*x*cos(x) \ 1 + x /
-atan(x)*cos(x) - -------- - ---------- + ----------------------------
2 2 2
1 + x / 2\ / 2\
\1 + x / \1 + x /
$$- \frac{6 x \cos{\left(x \right)}}{\left(x^{2} + 1\right)^{2}} - \cos{\left(x \right)} \operatorname{atan}{\left(x \right)} - \frac{3 \sin{\left(x \right)}}{x^{2} + 1} + \frac{2 \left(\frac{4 x^{2}}{x^{2} + 1} - 1\right) \left(\sin{\left(x \right)} + 2\right)}{\left(x^{2} + 1\right)^{2}}$$