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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 50 |
| 4 | 351 |
| 5 | 2457 |
| 6 | 17200 |
| 7 | 120401 |
| 8 | 842807 |
| 9 | 5899650 |
| 10 | 41297551 |
| 11 | 289082857 |
| 12 | 2023580000 |
| 13 | 14165060001 |
| 14 | 99155420007 |
| 15 | 694087940050 |
| 16 | 4858615580351 |
| 17 | 34010309062457 |
| 18 | 238072163437200 |
| 19 | 1666505144060401 |
| 20 | 11665536008422807 |
| 21 | 81658752058959650 |
| 22 | 571611264412717551 |
[1,7,50,351,2457,17200,120401,842807,5899650, 41297551,289082857,2023580000,14165060001, 99155420007,694087940050,4858615580351, 34010309062457,238072163437200,1666505144060401, 11665536008422807,81658752058959650, 571611264412717551] |