2*x*atan(x)
2*x 2*atan(x) + ------ 2 1 + x
/ 2 \ | x | 4*|1 - ------| | 2| \ 1 + x / -------------- 2 1 + x
/ 2 \ | x | 16*x*|-1 + ------| | 2| \ 1 + x / ------------------ 2 / 2\ \1 + x /