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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 8 |
| 5 | 38 |
| 6 | 141 |
| 7 | 455 |
| 8 | 1350 |
| 9 | 3805 |
| 10 | 10395 |
| 11 | 27875 |
| 12 | 73945 |
| 13 | 194961 |
| 14 | 512303 |
| 15 | 1343768 |
| 16 | 3521381 |
| 17 | 9223435 |
| 18 | 24152800 |
| 19 | 63239810 |
| 20 | 165572615 |
| 21 | 433485350 |
| 22 | 1134892290 |
| 23 | 2971202146 |
| 24 | 7778726798 |
| 25 | 20364993198 |
| 26 | 53316270346 |
| 27 | 139583838315 |
[1,8,38,141,455,1350,3805,10395,27875,73945, 194961,512303,1343768,3521381,9223435,24152800, 63239810,165572615,433485350,1134892290, 2971202146,7778726798,20364993198,53316270346, 139583838315] |