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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 10 |
| 6 | 25 |
| 7 | 98 |
| 8 | 304 |
| 9 | 1809 |
| 10 | 7930 |
| 11 | 72506 |
| 12 | 400613 |
| 13 | 5713422 |
| 14 | 40142648 |
| 15 | 888016669 |
| 16 | 8057185631 |
| 17 | 274304468798 |
| 18 | 3201392865337 |
| 19 | 169069430683773 |
| 20 | 2534673576738596 |
| 21 | 207045671219200314 |
| 22 | 3988243193242437962 |
| 23 | 504059170133969414707 |
[1,1,1,4,10,25,98,304,1809,7930,72506,400613, 5713422,40142648,888016669,8057185631, 274304468798,3201392865337,169069430683773, 2534673576738596,207045671219200314, 3988243193242437962,504059170133969414707] |