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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 42 |
| 4 | 234 |
| 5 | 1264 |
| 6 | 6776 |
| 7 | 36094 |
| 8 | 190560 |
| 9 | 997774 |
| 10 | 5199588 |
| 11 | 27025854 |
| 12 | 140092710 |
| 13 | 723510594 |
| 14 | 3720320512 |
| 15 | 19044051770 |
| 16 | 97051434120 |
| 17 | 492383872912 |
| 18 | 2486705768206 |
[1,7,42,234,1264,6776,36094,190560,997774,5199588, 27025854,140092710,723510594,3720320512, 19044051770,97051434120,492383872912, 2486705768206] |