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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 12 |
| 6 | 39 |
| 7 | 184 |
| 8 | 951 |
| 9 | 5531 |
| 10 | 38713 |
| 11 | 346207 |
| 12 | 3130812 |
| 13 | 34444964 |
| 14 | 382437428 |
| 15 | 4637235145 |
[0,0,0,1,3,12,39,184,951,5531,38713,346207, 3130812,34444964,382437428,4637235145] |