Number of ways to place 6 nonattacking bishops on a 6 X n board.

Terms

a(0) =1a(1) =16a(2) =313a(3) =2320a(4) =12160a(5) =53744a(6) =209428a(7) =683524a(8) =1905625a(9) =4664384a(10) =10297579a(11) =20907590a(12) =39664250a(13) =71114916a(14) =121559433a(15) =199459466a(16) =315906248a(17) =485124352a(18) =725031335a(19) =1057839684a(20) =1510706686a(21) =2116429956a(22) =2914190277a(23) =3950340692