# A308648 (b-file synthesized from sequence entry) 0 0 1 0 2 1 3 3 4 12 5 40 6 120 7 336 8 7168 9 58752 10 345600 11 1682560 12 15983616 13 142192128 14 2318697472 15 25614382080 16 282753361920 17 2645093410816 18 48869743454208 19 674729909839872 20 12153962014842880 21 167314499427532800 22 1986101341059956736 23 20335611320801886208