Number of lines through exactly 7 points of an n X n grid of points.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =16a(8) =4a(9) =4a(10) =4a(11) =4a(12) =4a(13) =32a(14) =68a(15) =48a(16) =20a(17) =20a(18) =20a(19) =100a(20) =196a(21) =308a(22) =252a(23) =180a(24) =92a(25) =196a(26) =316a(27) =452a(28) =604a(29) =532