# A006726 (b-file synthesized from sequence entry)
4 1
5 8
6 40
7 168
8 676
9 2672
10 10376
11 39824
12 151878
13 576656
14 2181496
15 8229160
16 30974700
17 116385088
18 436678520
19 1636472360
20 6126647748