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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 11 |
| 3 | 72 |
| 4 | 378 |
| 5 | 1755 |
| 6 | 7533 |
| 7 | 30618 |
| 8 | 119556 |
| 9 | 452709 |
| 10 | 1673055 |
| 11 | 6062364 |
| 12 | 21611934 |
| 13 | 75996063 |
| 14 | 264126177 |
| 15 | 908764110 |
| 16 | 3099363912 |
| 17 | 10489051017 |
| 18 | 35255264499 |
| 19 | 117775828656 |
| 20 | 391294693890 |
| 21 | 1293597012771 |
| 22 | 4257363753621 |
| 23 | 13954111172802 |
[0,1,11,72,378,1755,7533,30618,119556,452709, 1673055,6062364,21611934,75996063,264126177, 908764110,3099363912,10489051017,35255264499, 117775828656,391294693890,1293597012771, 4257363753621,13954111172802] |