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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 55 |
| 4 | 469 |
| 5 | 4237 |
| 6 | 39907 |
| 7 | 387739 |
| 8 | 3858505 |
| 9 | 39130777 |
| 10 | 402972031 |
| 11 | 4202705311 |
| 12 | 44299426717 |
| 13 | 471189693925 |
| 14 | 5051001609115 |
| 15 | 54513542257795 |
| 16 | 591858123926545 |
| 17 | 6459813793353265 |
| 18 | 70837427884259575 |
| 19 | 780073647992404615 |
[1,1,7,55,469,4237,39907,387739,3858505,39130777, 402972031,4202705311,44299426717,471189693925, 5051001609115,54513542257795,591858123926545, 6459813793353265,70837427884259575, 780073647992404615] |