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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 35 |
| 6 | 226 |
| 7 | 1645 |
| 8 | 13454 |
| 9 | 122661 |
| 10 | 1236018 |
| 11 | 13656951 |
| 12 | 164290182 |
| 13 | 2138379243 |
| 14 | 29949509226 |
| 15 | 449188719525 |
| 16 | 7183702249542 |
| 17 | 122039922034485 |
| 18 | 2194928052851898 |
| 19 | 41666342509646127 |
| 20 | 832547791827455886 |
| 21 | 17466905709043534107 |
| 22 | 383908421683657311714 |
[1,0,0,1,6,35,226,1645,13454,122661,1236018, 13656951,164290182,2138379243,29949509226, 449188719525,7183702249542,122039922034485, 2194928052851898,41666342509646127, 832547791827455886,17466905709043534107, 383908421683657311714] |