Number of ways to place 4 nonattacking kings on an n X n cylindrical chessboard.

Terms

a(0) =0a(1) =0a(2) =0a(3) =32a(4) =1205a(5) =13260a(6) =74494a(7) =291708a(8) =908973a(9) =2416410a(10) =5711530a(11) =12327414a(12) =24743693a(13) =46797968a(14) =84216990a(15) =145288600a(16) =241697109a(17) =389546478a(18) =610597338a(19) =933745570a(20) =1396771845a(21) =2048393204a(22) =2950649438a(23) =4181658708a(24) =5838778525a(25) =8042209890a(26) =10939084074a(27) =14708073198