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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 54 |
| 4 | 249 |
| 5 | 1177 |
| 6 | 5636 |
| 7 | 27249 |
| 8 | 132741 |
| 9 | 649642 |
| 10 | 3191756 |
| 11 | 15726012 |
| 12 | 77663557 |
| 13 | 384258080 |
| 14 | 1903995456 |
| 15 | 9445840534 |
| 16 | 46908432474 |
| 17 | 233146909282 |
| 18 | 1159624911004 |
| 19 | 5771215398000 |
| 20 | 28737003810563 |
| 21 | 143155655455776 |
| 22 | 713415855046229 |
| 23 | 3556494722952293 |
| 24 | 17734887091858891 |
| 25 | 88459818213824273 |
[1,3,12,54,249,1177,5636,27249,132741,649642, 3191756,15726012,77663557,384258080,1903995456, 9445840534,46908432474,233146909282,1159624911004, 5771215398000,28737003810563,143155655455776, 713415855046229,3556494722952293, 17734887091858891,88459818213824273] |