acot(2*x)
d --(acot(2*x)) dx
16*x
-----------
2
/ 2\
\1 + 4*x /
/ 2 \
| 16*x |
16*|1 - --------|
| 2|
\ 1 + 4*x /
-----------------
2
/ 2\
\1 + 4*x /