# A073986 (b-file synthesized from sequence entry)
1 0
2 2
3 9
4 54
5 300
6 1296
7 6300
8 39312
9 262440
10 1679616
11 10349856
12 62355744
13 369476640
14 2179768320
15 12958657344
16 77751944064
17 468419708160
18 2821109907456
19 16957996040448
20 101753146100736
21 609954817881600
22 3656158440062976
23 21926115464435712
24 131557435432187904