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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 103 |
| 6 | 377 |
| 7 | 1422 |
| 8 | 5565 |
| 9 | 21950 |
| 10 | 88820 |
| 11 | 363147 |
| 12 | 1507396 |
| 13 | 6318361 |
| 14 | 26732683 |
| 15 | 114043135 |
| 16 | 489990808 |
| 17 | 2119013654 |
| 18 | 9217370077 |
| 19 | 40299682605 |
| 20 | 177044960066 |
| 21 | 781085989055 |
| 22 | 3459695589433 |
| 23 | 15379323962591 |
| 24 | 68592071027709 |
| 25 | 306867228670406 |
| 26 | 1376739012758006 |
| 27 | 6193080192819522 |
| 28 | 27927074326121836 |
[1,1,3,9,30,103,377,1422,5565,21950,88820,363147, 1507396,6318361,26732683,114043135,489990808, 2119013654,9217370077,40299682605,177044960066, 781085989055,3459695589433,15379323962591, 68592071027709,306867228670406,1376739012758006, 6193080192819522,27927074326121836] |