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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 15 |
| 2 | 129 |
| 3 | 877 |
| 4 | 5280 |
| 5 | 29658 |
| 6 | 159742 |
| 7 | 838038 |
| 8 | 4323003 |
| 9 | 22057825 |
| 10 | 111750519 |
| 11 | 563535483 |
| 12 | 2833221970 |
| 13 | 14216330916 |
| 14 | 71243079660 |
| 15 | 356731958812 |
| 16 | 1785306330981 |
| 17 | 8931761831331 |
| 18 | 44675371382365 |
[1,15,129,877,5280,29658,159742,838038,4323003, 22057825,111750519,563535483,2833221970, 14216330916,71243079660,356731958812, 1785306330981,8931761831331,44675371382365] |