# A054873 (b-file synthesized from sequence entry)
1 1
2 2
3 6
4 24
5 120
6 720
7 5040
8 40320
9 357840
10 3427200
11 34685280
12 365541120
13 3971615760
14 44181889920
15 500788985760
16 5763231048960
17 67163932069920
18 791030794095360
19 9400660122813120
20 112587818898562560