Number of ways to place 4 nonattacking knights on an n X n cylindrical board.

Terms

a(0) =0a(1) =0a(2) =0a(3) =306a(4) =2365a(5) =19047a(6) =90503a(7) =328324a(8) =981693a(9) =2547955a(10) =5933257a(11) =12681288a(12) =25284363a(13) =47595023a(14) =85357395a(15) =146879312a(16) =243867873a(17) =392452803a(18) =614423653a(19) =938708560a(20) =1403123967a(21) =2056426383a(22) =2960698943a(23) =4194107208a(24) =5854060325