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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 7 |
| 5 | 78 |
| 6 | 420 |
| 7 | 6872 |
| 8 | 17253 |
| 9 | 326552 |
| 10 | 2680988 |
| 11 | 33949242 |
| 12 | 386091406 |
| 13 | 5974089338 |
| 14 | 67562271804 |
| 15 | 1708769998136 |
| 16 | 16983594666421 |
| 17 | 329723068729854 |
| 18 | 5611760457560028 |
| 19 | 121573316570762036 |
| 20 | 2099347805249971662 |
| 21 | 50720938223339101844 |
| 22 | 1008798617234428297708 |
[1,1,6,7,78,420,6872,17253,326552,2680988, 33949242,386091406,5974089338,67562271804, 1708769998136,16983594666421,329723068729854, 5611760457560028,121573316570762036, 2099347805249971662,50720938223339101844, 1008798617234428297708] |