# A006973 (b-file synthesized from sequence entry)
1 0
2 1
3 2
4 9
5 24
6 130
7 720
8 8505
9 35840
10 412776
11 3628800
12 42030450
13 479001600
14 7019298000
15 82614884352
16 1886805545625
17 20922789888000
18 374426276224000
19 6402373705728000
20 134987215801622184
21 2379913632645120000