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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 14 |
| 3 | 105 |
| 4 | 630 |
| 5 | 4850 |
| 6 | 31276 |
| 7 | 250592 |
| 8 | 1727836 |
| 9 | 13831303 |
| 10 | 99330350 |
| 11 | 789537708 |
| 12 | 5828000730 |
| 13 | 46064702150 |
| 14 | 346391183886 |
| 15 | 2727741658914 |
| 16 | 20778683750294 |
| 17 | 163289874109963 |
| 18 | 1255321900392396 |
| 19 | 9855914786067634 |
| 20 | 76271581305888386 |
[0,14,105,630,4850,31276,250592,1727836,13831303, 99330350,789537708,5828000730,46064702150, 346391183886,2727741658914,20778683750294, 163289874109963,1255321900392396,9855914786067634, 76271581305888386] |