Number of ways to place a non-attacking white and black queen on n X n chessboard.

Terms

a(0) =0a(1) =0a(2) =16a(3) =88a(4) =280a(5) =680a(6) =1400a(7) =2576a(8) =4368a(9) =6960a(10) =10560a(11) =15400a(12) =21736a(13) =29848a(14) =40040a(15) =52640a(16) =68000a(17) =86496a(18) =108528a(19) =134520a(20) =164920a(21) =200200a(22) =240856a(23) =287408a(24) =340400a(25) =400400a(26) =468000a(27) =543816a(28) =628488a(29) =722680