# A081050 (b-file synthesized from sequence entry) 0 1 1 0 2 5 3 5 4 74 5 154 6 2484 7 8028 8 149904 9 663696 10 14257440 11 80627040 12 1965444480 13 13575738240 14 370643938560 15 3031488633600 16 91657072281600 17 867718162483200 18 28779361764249600 19 309920046408806400 20 11185850044938240000