# A167532 (b-file synthesized from sequence entry)
0 1
1 2
2 2
3 8
4 20
5 112
6 432
7 3200
8 16704
9 154688
10 1017920
11 11333888
12 90011264
13 1172330496
14 10908526592
15 162802835456
16 1737036006400
17 29235365490688
18 351847501606912
19 6593866787569664
20 88364197074231296
21 1825016315965767680