A143876 Number of ways of placing kings with no more than 2 mutual attacks on an n X n chessboard symmetric under horizontal reflection.
1, 2, 3, 27, 26, 1119, 921, 122658, 74887, 43743593, 18775998, 43803694319, 14699916393, 143879089856822, 34113001129873
Offset: 0