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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 0 |
| 6 | 3 |
| 7 | 1 |
| 8 | 13 |
| 9 | 7 |
| 10 | 59 |
| 11 | 70 |
| 12 | 553 |
| 13 | 1277 |
| 14 | 7661 |
| 15 | 32395 |
| 16 | 199205 |
| 17 | 1149306 |
| 18 | 7752187 |
| 19 | 53913897 |
[0,0,0,1,0,3,1,13,7,59,70,553,1277,7661,32395, 199205,1149306,7752187,53913897] |