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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 24 |
| 4 | 103 |
| 5 | 416 |
| 6 | 1998 |
| 7 | 8822 |
| 8 | 45661 |
| 9 | 213674 |
| 10 | 1167797 |
| 11 | 5694690 |
| 12 | 32445914 |
| 13 | 163151262 |
| 14 | 960580840 |
| 15 | 4945645808 |
| 16 | 29899013071 |
| 17 | 156834641076 |
| 18 | 968947169139 |
[1,2,7,24,103,416,1998,8822,45661,213674,1167797, 5694690,32445914,163151262,960580840,4945645808, 29899013071,156834641076,968947169139] |