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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =12a(6) =46a(7) =140a(8) =344a(9) =732a(10) =1400a(11) =2468a(12) =4080a(13) =6404a(14) =9632a(15) =13980a(16) =19688a(17) =27020a(18) =36264a(19) =47732a(20) =61760a(21) =78708a(22) =98960a(23) =122924a(24) =151032a(25) =183740a(26) =221528a(27) =264900a(28) =314384a(29) =370532