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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 1 |
| 8 | 1 |
| 9 | 3 |
| 10 | 9 |
| 11 | 29 |
| 12 | 99 |
| 13 | 357 |
| 14 | 1351 |
| 15 | 5342 |
| 16 | 21983 |
| 17 | 93823 |
| 18 | 414198 |
| 19 | 1886424 |
| 20 | 8846390 |
| 21 | 42628782 |
| 22 | 210773592 |
| 23 | 1067599984 |
| 24 | 5533263752 |
| 25 | 29307314408 |
| 26 | 158484944416 |
| 27 | 874103230896 |
| 28 | 4913196556800 |
| 29 | 28120097476640 |
| 30 | 163770757573776 |
| 31 | 969858742317600 |
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