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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 70 |
| 5 | 440 |
| 6 | 3116 |
| 7 | 24274 |
| 8 | 204407 |
| 9 | 1836339 |
| 10 | 17425275 |
| 11 | 173329307 |
| 12 | 1796783304 |
| 13 | 19323703019 |
| 14 | 214843877103 |
| 15 | 2462522274426 |
| 16 | 29032815570544 |
| 17 | 351447240945518 |
| 18 | 4361579736404011 |
| 19 | 55424256247911490 |
| 20 | 720399315622779670 |
| 21 | 9569215299494074698 |
| 22 | 129799982362958621827 |
[1,1,3,13,70,440,3116,24274,204407,1836339, 17425275,173329307,1796783304,19323703019, 214843877103,2462522274426,29032815570544, 351447240945518,4361579736404011, 55424256247911490,720399315622779670, 9569215299494074698,129799982362958621827] |