# A000421 (b-file synthesized from sequence entry)
1 1
2 2
3 6
4 20
5 91
6 509
7 3608
8 31856
9 340416
10 4269971
11 61133757
12 978098997
13 17228295555
14 330552900516
15 6853905618223
16 152626436936272
17 3631575281503404
18 91928898608055819
19 2466448432564961852
20 69907637101781318907