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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 21 |
| 3 | 75 |
| 4 | 267 |
| 5 | 951 |
| 6 | 3387 |
| 7 | 12063 |
| 8 | 42963 |
| 9 | 153015 |
| 10 | 544971 |
| 11 | 1940943 |
| 12 | 6912771 |
| 13 | 24620199 |
| 14 | 87686139 |
| 15 | 312298815 |
| 16 | 1112268723 |
| 17 | 3961403799 |
| 18 | 14108748843 |
| 19 | 50249054127 |
| 20 | 178964660067 |
| 21 | 637392088455 |
| 22 | 2270105585499 |
| 23 | 8085100933407 |
| 24 | 28795513971219 |
[6,21,75,267,951,3387,12063,42963,153015,544971, 1940943,6912771,24620199,87686139,312298815, 1112268723,3961403799,14108748843,50249054127, 178964660067,637392088455,2270105585499, 8085100933407,28795513971219] |