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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 22 |
| 5 | 102 |
| 6 | 562 |
| 7 | 3618 |
| 8 | 26586 |
| 9 | 219798 |
| 10 | 2018686 |
| 11 | 20393790 |
| 12 | 224750298 |
| 13 | 2683250082 |
| 14 | 34498833434 |
| 15 | 475237879950 |
| 16 | 6983085189454 |
| 17 | 109021986683046 |
| 18 | 1802213242949602 |
| 19 | 31447143854808378 |
| 20 | 577609702827987882 |
| 21 | 11139837273501641502 |
| 22 | 225075546284489412854 |
[1,1,3,6,22,102,562,3618,26586,219798,2018686, 20393790,224750298,2683250082,34498833434, 475237879950,6983085189454,109021986683046, 1802213242949602,31447143854808378, 577609702827987882,11139837273501641502, 225075546284489412854] |