# A038154 (b-file synthesized from sequence entry)
0 0
1 0
2 2
3 12
4 60
5 320
6 1950
7 13692
8 109592
9 986400
10 9864090
11 108505100
12 1302061332
13 16926797472
14 236975164790
15 3554627472060
16 56874039553200
17 966858672404672
18 17403456103284402
19 330665665962403980
20 6613313319248079980
21 138879579704209680000