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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 35 |
| 5 | 541 |
| 6 | 13302 |
| 7 | 489287 |
| 8 | 25864897 |
| 9 | 1910753782 |
| 10 | 193328835393 |
| 11 | 26404671468121 |
| 12 | 4818917841228328 |
| 13 | 1167442027829857677 |
| 14 | 374059462390709800421 |
| 15 | 158311620026439080777076 |
[1,1,4,35,541,13302,489287,25864897,1910753782, 193328835393,26404671468121,4818917841228328, 1167442027829857677,374059462390709800421, 158311620026439080777076] |