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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 39 |
| 4 | 270 |
| 5 | 1959 |
| 6 | 14724 |
| 7 | 113706 |
| 8 | 896994 |
| 9 | 7198257 |
| 10 | 58580766 |
| 11 | 482345919 |
| 12 | 4011022800 |
| 13 | 33637868973 |
| 14 | 284174749008 |
| 15 | 2416159097325 |
| 16 | 20659453627698 |
| 17 | 177537776891964 |
| 18 | 1532534613873966 |
| 19 | 13282539993100539 |
| 20 | 115540763819844726 |
| 21 | 1008387790883534547 |
| 22 | 8827387038953362476 |
| 23 | 77488784299830377412 |
[1,6,39,270,1959,14724,113706,896994,7198257, 58580766,482345919,4011022800,33637868973, 284174749008,2416159097325,20659453627698, 177537776891964,1532534613873966, 13282539993100539,115540763819844726, 1008387790883534547,8827387038953362476, 77488784299830377412] |