Number of singly symmetric characteristic solutions to the n-queens problem.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =2a(7) =1a(8) =4a(9) =3a(10) =12a(11) =18a(12) =32a(13) =105a(14) =310a(15) =734a(16) =2006a(17) =4526a(18) =11046a(19) =36035a(20) =93740a(21) =312673a(22) =895310a(23) =2917938a(24) =8532332a(25) =28929567