# A006609 (b-file synthesized from sequence entry)
4 1
5 2
6 3
7 8
8 19
9 64
10 225
11 928
12 3441
13 17536
14 79259
15 454016
16 2424195
17 15628288
18 94471089
19 679156224
20 4613520889
21 36563599360