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

Terms

a(0) =0a(1) =6a(2) =36a(3) =112a(4) =276a(5) =582a(6) =1096a(7) =1896a(8) =3072a(9) =4726a(10) =6972a(11) =9936a(12) =13756a(13) =18582a(14) =24576a(15) =31912a(16) =40776a(17) =51366a(18) =63892a(19) =78576a(20) =95652a(21) =115366a(22) =137976a(23) =163752a(24) =192976a(25) =225942a(26) =262956a(27) =304336a(28) =350412a(29) =401526