Number of ways to place 4 nonattacking kings on a 4 X n board.

Terms

a(0) =0a(1) =0a(2) =9a(3) =79a(4) =454a(5) =1566a(6) =4103a(7) =9009a(8) =17484a(9) =30984a(10) =51221a(11) =80163a(12) =120034a(13) =173314a(14) =242739a(15) =331301a(16) =442248a(17) =579084a(18) =745569a(19) =945719a(20) =1183806a(21) =1464358a(22) =1792159a(23) =2172249a(24) =2609924a(25) =3110736a(26) =3680493a(27) =4325259a(28) =5051354a(29) =5865354