# A094304 (b-file synthesized from sequence entry)
1 1
2 0
3 1
4 4
5 18
6 96
7 600
8 4320
9 35280
10 322560
11 3265920
12 36288000
13 439084800
14 5748019200
15 80951270400
16 1220496076800
17 19615115520000
18 334764638208000
19 6046686277632000
20 115242726703104000
21 2311256907767808000
22 48658040163532800000
23 1072909785605898240000