Number of ways to place 3 nonattacking grasshoppers on a toroidal chessboard of size n x n.

Terms

a(0) =0a(1) =4a(2) =72a(3) =496a(4) =2100a(5) =6708a(6) =17640a(7) =40384a(8) =83376a(9) =158900a(10) =284108a(11) =482160a(12) =783484a(13) =1227156a(14) =1862400a(15) =2750208a(16) =3965080a(17) =5596884a(18) =7752836a(19) =10559600a(20) =14165508a(21) =18742900a(22) =24490584a(23) =31636416a(24) =40440000a(25) =51195508a(26) =64234620a(27) =79929584