Number of ways to place 3 nonattacking queens on a 3 X n board.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =4a(5) =14a(6) =36a(7) =76a(8) =140a(9) =234a(10) =364a(11) =536a(12) =756a(13) =1030a(14) =1364a(15) =1764a(16) =2236a(17) =2786a(18) =3420a(19) =4144a(20) =4964a(21) =5886a(22) =6916a(23) =8060a(24) =9324a(25) =10714a(26) =12236a(27) =13896a(28) =15700a(29) =17654