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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 9 |
| 6 | 36 |
| 7 | 157 |
| 8 | 758 |
| 9 | 3871 |
| 10 | 20582 |
| 11 | 112701 |
| 12 | 631039 |
| 13 | 3598161 |
| 14 | 20826912 |
| 15 | 122107107 |
[0,1,1,3,9,36,157,758,3871,20582,112701,631039, 3598161,20826912,122107107] |