Number of ways to select 3 or more collinear points from an n X n grid.

Terms

a(0) =0a(1) =0a(2) =8a(3) =54a(4) =228a(5) =708a(6) =1980a(7) =4890a(8) =11528a(9) =26004a(10) =57384a(11) =123786a(12) =265596a(13) =563664a(14) =1192220a(15) =2511474a(16) =5279208a(17) =11064216a(18) =23156448a(19) =48361110a(20) =100859180a(21) =209996772a(22) =436635396a(23) =906562842a(24) =1879950384a(25) =3893566872a(26) =8054935784a(27) =16645591974a(28) =34363631412a(29) =70872295524