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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 18 |
| 6 | 199 |
| 7 | 1756 |
| 8 | 13624 |
| 9 | 97434 |
| 10 | 659549 |
| 11 | 4294814 |
| 12 | 27187126 |
| 13 | 168499288 |
| 14 | 1027595830 |
| 15 | 6188801692 |
| 16 | 36907274904 |
| 17 | 218380550880 |
| 18 | 1284054213847 |
| 19 | 7511758730412 |
| 20 | 43762192338180 |
| 21 | 254086749470802 |
| 22 | 1471134871883972 |
[1,18,199,1756,13624,97434,659549,4294814, 27187126,168499288,1027595830,6188801692, 36907274904,218380550880,1284054213847, 7511758730412,43762192338180,254086749470802, 1471134871883972] |