# A002751 (b-file synthesized from sequence entry)
0 1
1 3
2 9
3 37
4 153
5 951
6 5473
7 42729
8 353937
9 3455083
10 30071001
11 426685293
12 4707929449
13 59350096287
14 882391484913
15 15177204356401
16 205119866263713
17 4040196156574419
18 64262949875511337
19 1408785031894483893
20 29514546353782633401
21 593055713389216814983