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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 28 |
| 3 | 477 |
| 4 | 15054 |
| 5 | 716619 |
| 6 | 46386636 |
| 7 | 3829544473 |
| 8 | 386956394842 |
| 9 | 46498297487679 |
| 10 | 6503866348955704 |
| 11 | 1041432998153210277 |
| 12 | 188367392877258840974 |
[1,4,28,477,15054,716619,46386636,3829544473, 386956394842,46498297487679,6503866348955704, 1041432998153210277,188367392877258840974] |