# A068201 (b-file synthesized from sequence entry)
0 1
1 2
2 6
3 24
4 120
5 720
6 4920
7 37320
8 309120
9 2763720
10 26440920
11 268864320
12 2889978120
13 32689371720
14 387638491920
15 4803456571320
16 62026296732120
17 832595493624720
18 11592967532632920
19 167119530011233320
20 2489936579950221120
21 38283169922493447720