# A087635 (b-file synthesized from sequence entry)
0 0
1 2
2 12
3 64
4 336
5 1760
6 9216
7 48256
8 252672
9 1323008
10 6927360
11 36272128
12 189923328
13 994451456
14 5207015424
15 27264286720
16 142757658624
17 747488804864
18 3913902194688
19 20493457948672
20 107305138913280
21 561857001684992