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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 3 |
| 4 | 12 |
| 5 | 21 |
| 6 | 57 |
| 7 | 120 |
| 8 | 291 |
| 9 | 651 |
| 10 | 1524 |
| 11 | 3477 |
| 12 | 8049 |
| 13 | 18480 |
| 14 | 42627 |
| 15 | 98067 |
| 16 | 225948 |
| 17 | 520149 |
| 18 | 1197993 |
| 19 | 2758440 |
| 20 | 6352419 |
| 21 | 14627739 |
| 22 | 33684996 |
| 23 | 77568213 |
| 24 | 178623201 |
| 25 | 411327840 |
| 26 | 947197443 |
| 27 | 2181180963 |
| 28 | 5022773292 |
| 29 | 11566316181 |
| 30 | 26634636057 |
[1,0,3,3,12,21,57,120,291,651,1524,3477,8049, 18480,42627,98067,225948,520149,1197993,2758440, 6352419,14627739,33684996,77568213,178623201, 411327840,947197443,2181180963,5022773292, 11566316181,26634636057] |