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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 44 |
| 6 | 133 |
| 7 | 398 |
| 8 | 1194 |
| 9 | 3582 |
| 10 | 10747 |
| 11 | 32240 |
| 12 | 96720 |
| 13 | 290159 |
| 14 | 870478 |
| 15 | 2611435 |
| 16 | 7834305 |
| 17 | 23502914 |
| 18 | 70508742 |
| 19 | 211526225 |
| 20 | 634578675 |
| 21 | 1903736026 |
| 22 | 5711208079 |
| 23 | 17133624236 |
| 24 | 51400872708 |
| 25 | 154202618124 |
| 26 | 462607854373 |
| 27 | 1387823563119 |
| 28 | 4163470689357 |
[0,1,2,5,15,44,133,398,1194,3582,10747,32240, 96720,290159,870478,2611435,7834305,23502914, 70508742,211526225,634578675,1903736026, 5711208079,17133624236,51400872708,154202618124, 462607854373,1387823563119,4163470689357] |