Bishops on an n X n board (see Robinson paper for details).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =8a(6) =16a(7) =40a(8) =72a(9) =260a(10) =432a(11) =1976a(12) =2880a(13) =17632a(14) =23040a(15) =177248a(16) =201600a(17) =2001680a(18) =2016000a(19) =24879520a(20) =21772800a(21) =338969216a(22) =261273600a(23) =5002865792a(24) =3353011200a(25) =79676972608a(26) =46942156800a(28) =697426329600