# A224078 (b-file synthesized from sequence entry)
1 2
2 6
3 12
4 60
5 120
6 360
7 2520
8 5040
9 55440
10 720720
11 1441440
12 4324320
13 21621600
14 367567200
15 6983776800
16 321253732800
17 6064949221531200
18 791245405339403414400
19 37188534050951960476800
20 581442729886633902054768000