# A083320 (b-file synthesized from sequence entry)
0 1
1 6
2 32
3 162
4 800
5 3906
6 18992
7 92322
8 449600
9 2195586
10 10755152
11 52845282
12 260386400
13 1286217666
14 6367168112
15 31576971042
16 156839811200
17 779990182146
18 3883029321872
19 19347201973602
20 96463456484000
21 481224744361026