# A001931 (b-file synthesized from sequence entry)
1 1
2 3
3 15
4 86
5 534
6 3481
7 23502
8 162913
9 1152870
10 8294738
11 60494549
12 446205905
13 3322769321
14 24946773111
15 188625900446
16 1435074454755
17 10977812452428
18 84384157287999
19 651459315795897
20 5049008190434659
21 39269513463794006
22 306405169166373418