# A307663 (b-file synthesized from sequence entry) 1 1 2 6 3 41 4 329 5 3090 6 33654 7 420792 8 5981688 9 95782320 10 1712555280 11 33909364800 12 737868052800 13 17521164259200 14 451126883894400 15 12522623670144000 16 372847351488998400 17 11853064556660275200 18 400718191717647820800 19 14354714544806716416000 20 543129329390299739136000 21 21642934280974058207232000