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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 57 |
| 4 | 1444 |
| 5 | 61785 |
| 6 | 4050126 |
| 7 | 373648513 |
| 8 | 47101090744 |
| 9 | 7764843893265 |
| 10 | 1630744323319450 |
| 11 | 426925697290933401 |
| 12 | 136591846585403311620 |
| 13 | 52602030074554601172649 |
| 14 | 24058544668572618782040022 |
| 15 | 12916480280574798627072144465 |
[1,1,4,57,1444,61785,4050126,373648513, 47101090744,7764843893265,1630744323319450, 426925697290933401,136591846585403311620, 52602030074554601172649, 24058544668572618782040022, 12916480280574798627072144465] |