# A020031 (b-file synthesized from sequence entry)
0 1
1 1
2 1
3 2
4 8
5 38
6 210
7 1380
8 10450
9 89574
10 857352
11 9063435
12 104876887
13 1318452295
14 17893281148
15 260730668151
16 4059948975491
17 67279154450986
18 1182190856781603
19 21954973054515490
20 429690186924088871