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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 92 |
| 5 | 625 |
| 6 | 4518 |
| 7 | 34067 |
| 8 | 264876 |
| 9 | 2108122 |
| 10 | 17089955 |
| 11 | 140620685 |
| 12 | 1171370236 |
| 13 | 9858740030 |
| 14 | 83708026208 |
| 15 | 716151866019 |
| 16 | 6167531084156 |
| 17 | 53424291896860 |
| 18 | 465157370556204 |
| 19 | 4068682850990824 |
| 20 | 35735239228966952 |
| 21 | 315031802838535433 |
| 22 | 2786616050168401350 |
[1,1,3,15,92,625,4518,34067,264876,2108122, 17089955,140620685,1171370236,9858740030, 83708026208,716151866019,6167531084156, 53424291896860,465157370556204,4068682850990824, 35735239228966952,315031802838535433, 2786616050168401350] |