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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 25 |
| 4 | 141 |
| 5 | 1465 |
| 6 | 23313 |
| 7 | 561044 |
| 8 | 20397794 |
| 9 | 1120217646 |
| 10 | 93298660085 |
| 11 | 11806084302586 |
| 12 | 2272026396983803 |
| 13 | 664988521276834246 |
[1,4,25,141,1465,23313,561044,20397794,1120217646, 93298660085,11806084302586,2272026396983803, 664988521276834246] |