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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 50 |
| 5 | 388 |
| 6 | 3363 |
| 7 | 31132 |
| 8 | 301156 |
| 9 | 3007000 |
| 10 | 30753169 |
| 11 | 320492869 |
| 12 | 3391067666 |
| 13 | 36331532588 |
| 14 | 393353506931 |
| 15 | 4296895624750 |
| 16 | 47300050998991 |
| 17 | 524168531729460 |
| 18 | 5842914510975105 |
| 19 | 65470405191871331 |
| 20 | 737008925038212059 |
| 21 | 8331166456981245521 |
[1,1,2,8,50,388,3363,31132,301156,3007000, 30753169,320492869,3391067666,36331532588, 393353506931,4296895624750,47300050998991, 524168531729460,5842914510975105, 65470405191871331,737008925038212059, 8331166456981245521] |