# A006818 (b-file synthesized from sequence entry)
0 1
1 6
2 30
3 150
4 738
5 3570
6 17118
7 81498
8 385710
9 1817046
10 8528478
11 39903462
12 186198642
13 866861394
14 4027766490
15 18681900270
16 86518735722
17 400136695074
18 1848320799438
19 8528448008214