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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 63 |
| 5 | 190 |
| 6 | 545 |
| 7 | 1433 |
| 8 | 3649 |
| 9 | 8828 |
| 10 | 20015 |
| 11 | 44641 |
| 12 | 95358 |
| 13 | 199081 |
| 14 | 412791 |
| 15 | 839638 |
| 16 | 1663449 |
[0,1,4,17,63,190,545,1433,3649,8828,20015,44641, 95358,199081,412791,839638,1663449] |