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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 35 |
| 4 | 457 |
| 5 | 12421 |
| 6 | 678101 |
| 7 | 69540142 |
| 8 | 13730026114 |
| 9 | 5551573311817 |
| 10 | 4379029522335786 |
| 11 | 6705866900012021577 |
| 12 | 21038900445652125741759 |
| 13 | 131183458646068931932668114 |
| 14 | 1603688863449847489871671547959 |
| 15 | 40294004792352613617780682256221711 |
[1,1,4,35,457,12421,678101,69540142,13730026114, 5551573311817,4379029522335786, 6705866900012021577,21038900445652125741759, 131183458646068931932668114, 1603688863449847489871671547959, 40294004792352613617780682256221711] |