# A153297 (b-file synthesized from sequence entry)
0 1
1 2
2 9
3 48
4 276
5 1656
6 10212
7 64190
8 409218
9 2637282
10 17143506
11 112224228
12 738926064
13 4889332266
14 32488240779
15 216664589058
16 1449568426292
17 9725637277248
18 65417353098837
19 441013558347228
20 2979206654245122