| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 28 |
| 5 | 90 |
| 6 | 297 |
| 7 | 1000 |
| 8 | 3417 |
| 9 | 11799 |
| 10 | 41041 |
| 11 | 143472 |
| 12 | 503262 |
| 13 | 1769365 |
| 14 | 6230304 |
| 15 | 21960801 |
| 16 | 77461435 |
| 17 | 273351705 |
| 18 | 964918116 |
| 19 | 3406804786 |
| 20 | 12029917377 |
| 21 | 42483179304 |
| 22 | 150036624217 |
| 23 | 529901048943 |
| 24 | 1871559855009 |
| 25 | 6610286313784 |
[1,3,9,28,90,297,1000,3417,11799,41041,143472, 503262,1769365,6230304,21960801,77461435, 273351705,964918116,3406804786,12029917377, 42483179304,150036624217,529901048943, 1871559855009,6610286313784] |