Number of ways to place n nonattacking composite pieces rook + rider[1,2] on an n X n chessboard.

A189837

Number of ways to place n nonattacking composite pieces rook + rider[1,2] on an n X n chessboard.

Terms

    a(0) =1a(1) =2a(2) =2a(3) =8a(4) =12a(5) =22a(6) =58a(7) =276a(8) =648a(9) =2304a(10) =6508a(11) =24528a(12) =96402a(13) =466922a(14) =2271738a(15) =13723826a(16) =76579326a(17) =512425626a(18) =3281233020a(19) =24654941268a(20) =175398054696

External references