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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 58 |
| 4 | 325 |
| 5 | 1686 |
| 6 | 8330 |
| 7 | 39796 |
| 8 | 185517 |
| 9 | 848830 |
| 10 | 3827230 |
| 11 | 17053356 |
| 12 | 75249954 |
| 13 | 329353948 |
| 14 | 1431575220 |
| 15 | 6185613032 |
| 16 | 26589395581 |
| 17 | 113780713806 |
| 18 | 484945025942 |
| 19 | 2059546425340 |
| 20 | 8719018250838 |
| 21 | 36805967321684 |
[0,1,9,58,325,1686,8330,39796,185517,848830, 3827230,17053356,75249954,329353948,1431575220, 6185613032,26589395581,113780713806,484945025942, 2059546425340,8719018250838,36805967321684] |