Number of geometrically distinct closed knight's tours of a 3 X n chessboard that have twofold symmetry.

A169768

Number of geometrically distinct closed knight's tours of a 3 X n chessboard that have twofold symmetry.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =4a(7) =0a(8) =0a(9) =0a(10) =24a(11) =0a(12) =24a(13) =0a(14) =276a(15) =0a(16) =176a(17) =0a(18) =2604a(19) =0a(20) =1876a(21) =0a(22) =25736a(23) =0a(24) =17384a(25) =0a(26) =248816a(27) =0a(28) =173064a(29) =0

External references