# A003613 (b-file synthesized from sequence entry)
1 1
2 6
3 12
4 96
5 1560
6 4848
7 28848
8 248352
9 1446240
10 12905664
11 99071040
12 649236480
13 4924099200
14 49007023872
15 304778309376
16 2301818168832
17 18389782387200
18 138110895596544
19 1094304243348480
20 8691945066848256
21 68039592521668608