# A188588 (b-file synthesized from sequence entry)
0 1
1 2
2 3
3 12
4 60
5 360
6 2520
7 20160
8 181440
9 1814400
10 19958400
11 239500800
12 3113510400
13 43589145600
14 653837184000
15 10461394944000
16 177843714048000
17 3201186852864000
18 60822550204416000
19 1216451004088320000
20 25545471085854720000