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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 33 |
| 4 | 115 |
| 5 | 401 |
| 6 | 1482 |
| 7 | 5449 |
| 8 | 20048 |
| 9 | 75303 |
| 10 | 283599 |
| 11 | 1069860 |
| 12 | 4070772 |
| 13 | 15539326 |
| 14 | 59433763 |
| 15 | 228278533 |
| 16 | 879053987 |
| 17 | 3391075968 |
| 18 | 13113667186 |
| 19 | 50808921375 |
| 20 | 197150760045 |
| 21 | 766241841810 |
| 22 | 2982295208876 |
| 23 | 11621280655944 |
[1,3,9,33,115,401,1482,5449,20048,75303,283599, 1069860,4070772,15539326,59433763,228278533, 879053987,3391075968,13113667186,50808921375, 197150760045,766241841810,2982295208876, 11621280655944] |