A130666 Number of ways of placing non-attacking knights on an n X n chessboard symmetric about both diagonal and antidiagonal.

1, 2, 4, 10, 21, 89, 248, 1652, 5760, 59789, 268529, 4367552, 24922412, 641484896, 4607113999, 188770443286, 1702258930069, 111575238563044, 1256539208451845, 132483845142611245, 1854392449274745630, 316017552098202250347