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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 22 |
| 4 | 82 |
| 5 | 320 |
| 6 | 1268 |
| 7 | 5102 |
| 8 | 20632 |
| 9 | 83972 |
| 10 | 342468 |
| 11 | 1399296 |
| 12 | 5720966 |
| 13 | 23396618 |
| 14 | 95654386 |
| 15 | 390868900 |
| 16 | 1596000418 |
| 17 | 6511211718 |
| 18 | 26538617050 |
| 19 | 108060466284 |
[1,2,6,22,82,320,1268,5102,20632,83972,342468, 1399296,5720966,23396618,95654386,390868900, 1596000418,6511211718,26538617050,108060466284] |