SP4178 LATTICE - Distance on a square lattice

Let L to be an _nXn_ square lattice, you can consider its points as _(x,y)_, where _x_ and _y_ are integers from the \[1,_n_\] interval. And let f(_n_) to be the expected distance between two not neccesserily distinct points on the lattice. For example f(1)=0 and f(2)=(2 + √ 2 )/4.

There is no input.

5000 lines, on the n-th line give the value of f(_n_) by 2 digits after the decimal point.