Number of ways of placing n nonattacking queens on an n X n toroidal chessboard.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =10a(5) =0a(6) =28a(7) =0a(8) =0a(9) =0a(10) =88a(11) =0a(12) =4524a(13) =0a(14) =0a(15) =0a(16) =140692a(17) =0a(18) =820496a(19) =0a(20) =0a(21) =0a(22) =128850048a(23) =0a(24) =1957725000a(25) =0a(26) =0a(27) =0a(28) =605917055356a(29) =0