let
t=ex⟹dt=exdx⟹dx=tdt
∫t3arctantdt
u=arctant⟹du=1+t2dt
dv=t3dt⟹v=−2t21
∫udv=u⋅v−∫vdu
proceed with the above integration by parts as recommended by the Banana. Note that another iteration of integration by parts for the (v du) integral may be needed.