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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 21 |
| 3 | 75 |
| 4 | 267 |
| 5 | 938 |
| 6 | 3283 |
| 7 | 11516 |
| 8 | 40399 |
| 9 | 141745 |
| 10 | 497298 |
| 11 | 1744684 |
| 12 | 6121152 |
| 13 | 21475315 |
| 14 | 75342932 |
| 15 | 264330011 |
| 16 | 927363850 |
| 17 | 3253519870 |
| 18 | 11414498822 |
| 19 | 40046099291 |
| 20 | 140495874086 |
| 21 | 492909198404 |
| 22 | 1729299730308 |
| 23 | 6066994825927 |
| 24 | 21285162746386 |
[6,21,75,267,938,3283,11516,40399,141745,497298, 1744684,6121152,21475315,75342932,264330011, 927363850,3253519870,11414498822,40046099291, 140495874086,492909198404,1729299730308, 6066994825927,21285162746386] |