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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 7 |
| 4 | 9 |
| 5 | 21 |
| 6 | 268 |
| 7 | 491 |
| 8 | 1893 |
| 9 | 5809 |
| 10 | 166476 |
| 11 | 373275 |
| 12 | 1812374 |
| 13 | 8077317 |
| 14 | 38851660 |
| 15 | 1934306029 |
| 16 | 5374689421 |
| 17 | 30125069097 |
| 18 | 152234643292 |
| 19 | 991832638619 |
| 20 | 5660219512530 |
| 21 | 516732891172537 |
| 22 | 1664067117563368 |
[1,2,1,7,9,21,268,491,1893,5809,166476,373275, 1812374,8077317,38851660,1934306029,5374689421, 30125069097,152234643292,991832638619, 5660219512530,516732891172537,1664067117563368] |