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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 243 |
| 5 | 2992 |
| 6 | 45906 |
| 7 | 845287 |
| 8 | 18182926 |
| 9 | 440710385 |
| 10 | 11876274391 |
| 11 | 351546957499 |
| 12 | 11330575607067 |
| 13 | 394862762014644 |
| 14 | 14792903605828298 |
| 15 | 592835563146850723 |
| 16 | 25306351970600498930 |
| 17 | 1146305330627242918543 |
| 18 | 54914971513967144548105 |
| 19 | 2773947252964889935144249 |
[1,1,4,26,243,2992,45906,845287,18182926, 440710385,11876274391,351546957499,11330575607067, 394862762014644,14792903605828298, 592835563146850723,25306351970600498930, 1146305330627242918543,54914971513967144548105, 2773947252964889935144249] |