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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 115 |
| 5 | 813 |
| 6 | 7627 |
| 7 | 71173 |
| 8 | 740023 |
| 9 | 8544169 |
| 10 | 107195083 |
| 11 | 1434581205 |
| 12 | 20499413667 |
| 13 | 312262663989 |
| 14 | 4992164670007 |
| 15 | 84221279919193 |
| 16 | 1492818584618099 |
| 17 | 27607818180267269 |
| 18 | 533522844488072987 |
| 19 | 10724970103003953053 |
| 20 | 223859943086157531063 |
| 21 | 4847766598150865273721 |
[1,1,3,21,115,813,7627,71173,740023,8544169, 107195083,1434581205,20499413667,312262663989, 4992164670007,84221279919193,1492818584618099, 27607818180267269,533522844488072987, 10724970103003953053,223859943086157531063, 4847766598150865273721] |