Number of ways of placing non-attacking knights on an n X n chessboard symmetric about the diagonal and under 90-degree rotation.

A130712

Number of ways of placing non-attacking knights on an n X n chessboard symmetric about the diagonal and under 90-degree rotation.

Terms

    a(0) =1a(1) =2a(2) =2a(3) =6a(4) =3a(5) =21a(6) =12a(7) =118a(8) =56a(9) =959a(10) =333a(11) =9892a(12) =3038a(13) =154506a(14) =38869a(15) =3291314a(16) =689349a(17) =103050492a(18) =17202265a(19) =4328976863a(20) =615532072a(21) =271539093065a(22) =30694296121

External references