“…We now use the known estimates for N (n). So in [Hardy 1999] an estimate of Gauss is given, showing that the number N (n) is equal to the area of the figure composed of unit squares of the lattice, for which the lower left corner lies in the circle C n . Since the greatest distance between the points of the unit square does not exceed √ 2, all unit squares that intersect the boundary of the circle C n are located in the ring…”