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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 48 |
| 3 | 204 |
| 4 | 765 |
| 5 | 2649 |
| 6 | 8680 |
| 7 | 27312 |
| 8 | 83313 |
| 9 | 247985 |
| 10 | 723624 |
| 11 | 2077164 |
| 12 | 5880797 |
| 13 | 16454865 |
| 14 | 45577200 |
| 15 | 125130432 |
| 16 | 340882113 |
| 17 | 922265721 |
| 18 | 2479938368 |
| 19 | 6631802220 |
| 20 | 17646603933 |
| 21 | 46744464745 |
| 22 | 123314065944 |
| 23 | 324085913136 |
| 24 | 848801213425 |
[1,9,48,204,765,2649,8680,27312,83313,247985, 723624,2077164,5880797,16454865,45577200, 125130432,340882113,922265721,2479938368, 6631802220,17646603933,46744464745,123314065944, 324085913136,848801213425] |