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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 29 |
| 4 | 180 |
| 5 | 1162 |
| 6 | 7698 |
| 7 | 51950 |
| 8 | 355531 |
| 9 | 2460224 |
| 10 | 17178755 |
| 11 | 120861710 |
| 12 | 855828960 |
| 13 | 6094211829 |
| 14 | 43610311298 |
| 15 | 313449094851 |
| 16 | 2261820356684 |
| 17 | 16379528485200 |
| 18 | 119003715014955 |
| 19 | 867198605427231 |
| 20 | 6336861345197670 |
[1,1,5,29,180,1162,7698,51950,355531,2460224, 17178755,120861710,855828960,6094211829, 43610311298,313449094851,2261820356684, 16379528485200,119003715014955,867198605427231, 6336861345197670] |