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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 57 |
| 4 | 658 |
| 5 | 8442 |
| 6 | 115692 |
| 7 | 1658505 |
| 8 | 24565530 |
| 9 | 372999198 |
| 10 | 5774883348 |
| 11 | 90821581578 |
| 12 | 1446901409268 |
| 13 | 23301338376916 |
| 14 | 378711707274072 |
| 15 | 6203898306232233 |
| 16 | 102329366764727658 |
| 17 | 1698047225583890550 |
| 18 | 28327664136201303300 |
| 19 | 474821679792884860590 |
| 20 | 7992739387298462213340 |
[0,1,6,57,658,8442,115692,1658505,24565530, 372999198,5774883348,90821581578,1446901409268, 23301338376916,378711707274072,6203898306232233, 102329366764727658,1698047225583890550, 28327664136201303300,474821679792884860590, 7992739387298462213340] |