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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 28 |
| 4 | 209 |
| 5 | 1826 |
| 6 | 18217 |
| 7 | 203106 |
| 8 | 2487361 |
| 9 | 33077566 |
| 10 | 473318201 |
| 11 | 7234847126 |
| 12 | 117435618577 |
| 13 | 2014339775800 |
| 14 | 36360190887217 |
| 15 | 688237505878726 |
| 16 | 13618646813974785 |
| 17 | 280960214041690038 |
| 18 | 6028928694559721305 |
| 19 | 134277542969681115870 |
| 20 | 3098232871805383942801 |
[1,1,5,28,209,1826,18217,203106,2487361,33077566, 473318201,7234847126,117435618577,2014339775800, 36360190887217,688237505878726,13618646813974785, 280960214041690038,6028928694559721305, 134277542969681115870,3098232871805383942801] |