Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric about both diagonal and antidiagonal.

A143879

Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric about both diagonal and antidiagonal.

Terms

    a(0) =1a(1) =2a(2) =3a(3) =7a(4) =12a(5) =41a(6) =85a(7) =434a(8) =1009a(9) =7325a(10) =21498a(11) =219307a(12) =803859a(13) =11370922

External references