# A173841 (b-file synthesized from sequence entry)
0 1
1 1
2 0
3 2
4 8
5 48
6 240
7 1968
8 13824
9 140160
10 1263360
11 15298560
12 168422400
13 2373073920
14 30865121280
15 496199854080
16 7445355724800
17 134510244986880
18 2287168006717440
19 45877376537395200
20 871804170613555200
21 19225435113632563200
22 403779880746418176000