# A052655 (b-file synthesized from sequence entry)
0 0
1 1
2 6
3 18
4 96
5 600
6 4320
7 35280
8 322560
9 3265920
10 36288000
11 439084800
12 5748019200
13 80951270400
14 1220496076800
15 19615115520000
16 334764638208000
17 6046686277632000
18 115242726703104000
19 2311256907767808000