Number of ways to place 3 nonattacking kings on an n X n cylindrical chessboard.

Terms

a(0) =0a(1) =0a(2) =0a(3) =88a(4) =785a(5) =3528a(6) =11151a(7) =28560a(8) =63513a(9) =127520a(10) =236863a(11) =413736a(12) =687505a(13) =1096088a(14) =1687455a(15) =2521248a(16) =3670521a(17) =5223600a(18) =7286063a(19) =9982840a(20) =13460433a(21) =17889256a(22) =23466095a(23) =30416688a(24) =38998425a(25) =49503168a(26) =62260191a(27) =77639240a(28) =96053713a(29) =117963960