# A004528 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 4
4 8
5 24
6 96
7 384
8 1536
9 7680
10 46080
11 276480
12 1658880
13 11612160
14 92897280
15 743178240
16 5945425920
17 53508833280
18 535088332800
19 5350883328000
20 53508833280000
21 588597166080000
22 7063165992960000