# A337071 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 6
4 40
5 264
6 3776
7 40256
8 1168000
9 34204032
10 1107791872
11 23233380352
12 1486675898368
13 38934372315136
14 1999103691427840
15 132874800979423232
16 20506322412604129280
17 776179999255323115520
18 107455579038104865996800
19 4651534843901106606571520
20 731092060557632280262082560