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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 154 |
| 4 | 1827 |
| 5 | 23562 |
| 6 | 320866 |
| 7 | 4540200 |
| 8 | 66096459 |
| 9 | 983592304 |
| 10 | 14894775896 |
| 11 | 228784720710 |
| 12 | 3555866673450 |
| 13 | 55819631671902 |
| 14 | 883738853546472 |
| 15 | 14094715154157680 |
| 16 | 226245021605612955 |
| 17 | 3652242142988400570 |
| 18 | 59254515909624764575 |
| 19 | 965678197027521177200 |
[1,2,15,154,1827,23562,320866,4540200,66096459, 983592304,14894775896,228784720710,3555866673450, 55819631671902,883738853546472,14094715154157680, 226245021605612955,3652242142988400570, 59254515909624764575,965678197027521177200] |