Number of ways to place 2 nonattacking bishops on an n X n toroidal board.

Terms

a(0) =0a(1) =4a(2) =18a(3) =80a(4) =200a(5) =468a(6) =882a(7) =1600a(8) =2592a(9) =4100a(10) =6050a(11) =8784a(12) =12168a(13) =16660a(14) =22050a(15) =28928a(16) =36992a(17) =46980a(18) =58482a(19) =72400a(20) =88200a(21) =106964a(22) =128018a(23) =152640a(24) =180000