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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 27 |
| 5 | 90 |
| 6 | 319 |
| 7 | 1133 |
| 8 | 4205 |
| 9 | 15759 |
| 10 | 60427 |
| 11 | 233074 |
| 12 | 913214 |
| 13 | 3602736 |
| 14 | 14365891 |
| 15 | 57610031 |
| 16 | 232900379 |
| 17 | 946343007 |
| 18 | 3869179663 |
| 19 | 15888284571 |
| 20 | 65568408186 |
| 21 | 271629504874 |
| 22 | 1129897836137 |
| 23 | 4715762928864 |
| 24 | 19749860841934 |
| 25 | 82957158492855 |
| 26 | 349484850458876 |
| 27 | 1476158463333397 |
| 28 | 6251072188077864 |
[1,1,3,8,27,90,319,1133,4205,15759,60427,233074, 913214,3602736,14365891,57610031,232900379, 946343007,3869179663,15888284571,65568408186, 271629504874,1129897836137,4715762928864, 19749860841934,82957158492855,349484850458876, 1476158463333397,6251072188077864] |