# A020128 (b-file synthesized from sequence entry)
0 1
1 1
2 1
3 3
4 9
5 42
6 232
7 1528
8 11611
9 99851
10 958562
11 10160756
12 117864769
13 1485096082
14 20197306709
15 294880677942
16 4600138575888
17 76362300359741
18 1343976486331426
19 24997962645764523
20 489960067856984639