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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 26 |
| 3 | 135 |
| 4 | 701 |
| 5 | 3640 |
| 6 | 18901 |
| 7 | 98145 |
| 8 | 509626 |
| 9 | 2646275 |
| 10 | 13741001 |
| 11 | 71351280 |
| 12 | 370497401 |
| 13 | 1923838285 |
| 14 | 9989688826 |
| 15 | 51872282415 |
| 16 | 269351100901 |
| 17 | 1398627786920 |
| 18 | 7262490035501 |
| 19 | 37711077964425 |
| 20 | 195817879857626 |
[1,5,26,135,701,3640,18901,98145,509626,2646275, 13741001,71351280,370497401,1923838285,9989688826, 51872282415,269351100901,1398627786920, 7262490035501,37711077964425,195817879857626] |