# A037788 (b-file synthesized from sequence entry)
1 3
2 20
3 120
4 721
5 4329
6 25976
7 155856
8 935137
9 5610825
10 33664952
11 201989712
12 1211938273
13 7271629641
14 43629777848
15 261778667088
16 1570672002529
17 9424032015177
18 56544192091064
19 339265152546384
20 2035590915278305