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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 4 |
| 5 | 10 |
| 6 | 19 |
| 7 | 34 |
| 8 | 55 |
| 9 | 406 |
| 10 | 2950 |
| 11 | 17731 |
| 12 | 91675 |
| 13 | 408976 |
| 14 | 3333241 |
| 15 | 44182549 |
| 16 | 642260617 |
| 17 | 9294897961 |
| 18 | 125470980640 |
| 19 | 2040625065922 |
| 20 | 47345357523907 |
| 21 | 1393444080049042 |
[1,4,10,19,34,55,406,2950,17731,91675,408976, 3333241,44182549,642260617,9294897961, 125470980640,2040625065922,47345357523907, 1393444080049042] |