Number of ways to place 3 nonattacking knights on an n X n cylindrical board.

Terms

a(0) =0a(1) =0a(2) =6a(3) =240a(4) =1010a(5) =4056a(6) =12068a(7) =30000a(8) =65628a(9) =130480a(10) =240856a(11) =418968a(12) =694200a(13) =1104488a(14) =1697820a(15) =2533856a(16) =3685668a(17) =5241600a(18) =7307248a(19) =10007560a(20) =13489056a(21) =17922168a(22) =23503700a(23) =30459408a(24) =39046700a(25) =49557456a(26) =62320968a(27) =77707000a(28) =96128968a(29) =118047240