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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 6 |
| 3 | 6 |
| 4 | 36 |
| 5 | 88 |
| 6 | 376 |
| 7 | 1096 |
| 8 | 4476 |
| 9 | 14200 |
| 10 | 57284 |
| 11 | 190206 |
| 12 | 764812 |
| 13 | 2615268 |
| 14 | 10499504 |
| 15 | 36677626 |
| 16 | 147110276 |
| 17 | 522288944 |
[1,0,6,6,36,88,376,1096,4476,14200,57284,190206, 764812,2615268,10499504,36677626,147110276, 522288944] |