Number of points of norm^2 <= n^2 in the square lattice that are visible from the origin.

Terms

a(0) =1a(1) =5a(2) =9a(3) =17a(4) =33a(5) =49a(6) =73a(7) =89a(8) =121a(9) =153a(10) =193a(11) =225a(12) =265a(13) =313a(14) =385a(15) =441a(16) =481a(17) =545a(18) =617a(19) =673a(20) =769a(21) =833a(22) =929a(23) =1001a(24) =1113a(25) =1193a(26) =1281a(27) =1385a(28) =1489a(29) =1585