Number of ways to place 2 nonattacking amazons (superqueens) on an n X n board.

Terms

a(0) =0a(1) =0a(2) =0a(3) =20a(4) =92a(5) =260a(6) =580a(7) =1120a(8) =1960a(9) =3192a(10) =4920a(11) =7260a(12) =10340a(13) =14300a(14) =19292a(15) =25480a(16) =33040a(17) =42160a(18) =53040a(19) =65892a(20) =80940a(21) =98420a(22) =118580a(23) =141680a(24) =167992a(25) =197800a(26) =231400a(27) =269100a(28) =311220a(29) =358092