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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 11 |
| 6 | 36 |
| 7 | 122 |
| 8 | 538 |
| 9 | 2526 |
| 10 | 13166 |
| 11 | 71153 |
| 12 | 400109 |
| 13 | 2300430 |
| 14 | 13504780 |
| 15 | 80547558 |
| 16 | 487327904 |
[0,1,2,5,11,36,122,538,2526,13166,71153,400109, 2300430,13504780,80547558,487327904] |