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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 40 |
| 4 | 201 |
| 5 | 1008 |
| 6 | 5040 |
| 7 | 25201 |
| 8 | 126008 |
| 9 | 630040 |
| 10 | 3150201 |
| 11 | 15751008 |
| 12 | 78755040 |
| 13 | 393775201 |
| 14 | 1968876008 |
| 15 | 9844380040 |
| 16 | 49221900201 |
| 17 | 246109501008 |
| 18 | 1230547505040 |
| 19 | 6152737525201 |
| 20 | 30763687626008 |
| 21 | 153818438130040 |
| 22 | 769092190650201 |
[1,8,40,201,1008,5040,25201,126008,630040,3150201, 15751008,78755040,393775201,1968876008,9844380040, 49221900201,246109501008,1230547505040, 6152737525201,30763687626008,153818438130040, 769092190650201] |