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

Terms

a(0) =0a(1) =4a(2) =36a(3) =276a(4) =1152a(5) =3920a(6) =10568a(7) =25348a(8) =53848a(9) =106292a(10) =194732a(11) =339416a(12) =562652a(13) =899796a(14) =1388008a(15) =2083908a(16) =3044992a(17) =4356344a(18) =6102144a(19) =8404204a(20) =11380564a(21) =15199100a(22) =20019856a(23) =26067112a(24) =33551812a(25) =42766092a(26) =53981600a(27) =67570804