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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 22 |
| 6 | 58 |
| 7 | 160 |
| 8 | 454 |
| 9 | 1311 |
| 10 | 3828 |
| 11 | 11260 |
| 12 | 33290 |
| 13 | 98778 |
| 14 | 293866 |
| 15 | 875960 |
| 16 | 2614891 |
| 17 | 7814544 |
| 18 | 23373354 |
| 19 | 69955372 |
| 20 | 209478678 |
| 21 | 627521578 |
| 22 | 1880400340 |
| 23 | 5636065932 |
| 24 | 16895989570 |
| 25 | 50658893073 |
[1,2,4,9,22,58,160,454,1311,3828,11260,33290, 98778,293866,875960,2614891,7814544,23373354, 69955372,209478678,627521578,1880400340, 5636065932,16895989570,50658893073] |