A143871 Number of ways of placing kings with no more than 1 mutual attack on an n X n chessboard symmetric under horizontal reflection.
1, 2, 3, 13, 18, 425, 371, 27872, 25147, 8144945, 4679546, 6097351181, 3118820527, 16876586891126, 6022295415137
Offset: 0