%N Number of unit squares at least 50% covered by a circle inscribed in an integer square of size n X n.
%C From _Robert G. Wilson v_, Mar 20 2017: (Start)
%C For n odd, the center of the circle is in the middle of the center square and thus a(2n-1) == 1 (mod 4).
%C For n even, the center of the circle is at the four corners of the center 4 squares and thus a(2n) == 0 (mod 4). (End)
%e a(2)=4 because an inscribed circle in a 2 X 2 grid covers 50% of all the unit squares within it.
%A Joe K. Crump (joecr(AT)carolina.rr.com)