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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 28 |
| 5 | 200 |
| 6 | 1686 |
| 7 | 14322 |
| 8 | 120856 |
| 9 | 1046376 |
| 10 | 10250890 |
| 11 | 150231950 |
| 12 | 3231032388 |
| 13 | 63012862068 |
| 14 | 578740591534 |
| 15 | -16721732074110 |
| 16 | -795532873957712 |
| 17 | -563556173628880 |
| 18 | 1315395887469186834 |
| 19 | 58144603365684119574 |
| 20 | -114890208409408898660 |
| 21 | -145164771250945501267380 |
[1,2,6,28,200,1686,14322,120856,1046376,10250890, 150231950,3231032388,63012862068,578740591534, -16721732074110,-795532873957712,-563556173628880, 1315395887469186834,58144603365684119574, -114890208409408898660,-145164771250945501267380] |