Number of ways to place 2n nonattacking kings on a 4 X 2n cylindrical chessboard.

A194644

Number of ways to place 2n nonattacking kings on a 4 X 2n cylindrical chessboard.

Terms

    a(0) =12a(1) =32a(2) =90a(3) =256a(4) =732a(5) =2102a(6) =6060a(7) =17536a(8) =50922a(9) =148352a(10) =433500a(11) =1270246a(12) =3731532a(13) =10987232a(14) =32418810a(15) =95835136a(16) =283784412a(17) =841611542a(18) =2499330540a(19) =7431221056a(20) =22118855562a(21) =65898914432a(22) =196498594140a(23) =586358987206

External references