# A152668 (b-file synthesized from sequence entry)
2 2
3 6
4 36
5 192
6 1440
7 10800
8 100800
9 967680
10 10886400
11 127008000
12 1676505600
13 22992076800
14 348713164800
15 5492232345600
16 94152554496000
17 1673823191040000
18 32011868528640000
19 633834996867072000
20 13380961044971520000