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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 46 |
| 4 | 253 |
| 5 | 1452 |
| 6 | 8570 |
| 7 | 51594 |
| 8 | 315225 |
| 9 | 1948010 |
| 10 | 12147881 |
| 11 | 76316508 |
| 12 | 482392198 |
| 13 | 3064987460 |
| 14 | 19560379470 |
| 15 | 125309993974 |
| 16 | 805458510441 |
| 17 | 5192500350906 |
| 18 | 33561539356277 |
| 19 | 217429403317006 |
| 20 | 1411572472199649 |
| 21 | 9181398851046632 |
| 22 | 59821825063376124 |
| 23 | 390382132833183204 |
[1,2,9,46,253,1452,8570,51594,315225,1948010, 12147881,76316508,482392198,3064987460, 19560379470,125309993974,805458510441, 5192500350906,33561539356277,217429403317006, 1411572472199649,9181398851046632, 59821825063376124,390382132833183204] |