Primitive of Arctangent of x over a over x

Also see

 * Primitive of $\dfrac 1 x \arcsin \dfrac x a$


 * Primitive of $\dfrac 1 x \arccos \dfrac x a$


 * Primitive of $\dfrac 1 x \arccot \dfrac x a$


 * Primitive of $\dfrac 1 x \arcsec \dfrac x a$


 * Primitive of $\dfrac 1 x \arccsc \dfrac x a$