# A198892 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 9
4 48
5 300
6 2280
7 20580
8 211680
9 2434320
10 31134600
11 438807600
12 6744276000
13 112237725600
14 2011760150400
15 38639999197800
16 791610365145600
17 17230493212732800
18 397111119429024000
19 9660782144094681600
20 247393077222459168000
21 6651976858409613931200