Number of asymmetric characteristic solutions to the n-queens problem.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =0a(6) =4a(7) =11a(8) =42a(9) =89a(10) =329a(11) =1765a(12) =9197a(13) =45647a(14) =284743a(15) =1846189a(16) =11975869a(17) =83259065a(18) =621001708a(19) =4878630533a(20) =39333230881a(21) =336375931369