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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 30 |
| 4 | 144 |
| 5 | 728 |
| 6 | 3879 |
| 7 | 21338 |
| 8 | 120301 |
| 9 | 691482 |
| 10 | 4037020 |
| 11 | 23873308 |
| 12 | 142702222 |
| 13 | 860823760 |
| 14 | 5233702949 |
| 15 | 32038319854 |
| 16 | 197302553658 |
| 17 | 1221511228130 |
| 18 | 7598234842024 |
| 19 | 47464203317986 |
| 20 | 297630203452010 |
| 21 | 1872792573164662 |
| 22 | 11821420702394153 |
| 23 | 74834134991237178 |
[1,2,7,30,144,728,3879,21338,120301,691482, 4037020,23873308,142702222,860823760,5233702949, 32038319854,197302553658,1221511228130, 7598234842024,47464203317986,297630203452010, 1872792573164662,11821420702394153, 74834134991237178] |