Number of lines through at least 2 points of an n X n grid of points.

Terms

a(0) =0a(1) =0a(2) =6a(3) =20a(4) =62a(5) =140a(6) =306a(7) =536a(8) =938a(9) =1492a(10) =2306a(11) =3296a(12) =4722a(13) =6460a(14) =8830a(15) =11568a(16) =14946a(17) =18900a(18) =23926a(19) =29544a(20) =36510a(21) =44388a(22) =53586a(23) =63648a(24) =75674a(25) =88948a(26) =104374a(27) =121032a(28) =139966a(29) =160636