# A052591 (b-file synthesized from sequence entry)
0 0
1 1
2 2
3 12
4 48
5 360
6 2160
7 20160
8 161280
9 1814400
10 18144000
11 239500800
12 2874009600
13 43589145600
14 610248038400
15 10461394944000
16 167382319104000
17 3201186852864000
18 57621363351552000
19 1216451004088320000
20 24329020081766400000
21 562000363888803840000