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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 12 |
| 3 | 138 |
| 4 | 1555 |
| 5 | 17577 |
| 6 | 200157 |
| 7 | 2295840 |
| 8 | 26499448 |
| 9 | 307489800 |
| 10 | 3583945822 |
| 11 | 41930931927 |
| 12 | 492166822386 |
| 13 | 5792986378880 |
| 14 | 68351501389096 |
| 15 | 808201629781063 |
| 16 | 9574366418412669 |
| 17 | 113613225065827244 |
| 18 | 1350205860499349690 |
| 19 | 16067869695882894095 |
| 20 | 191446722937160655101 |
[1,1,12,138,1555,17577,200157,2295840,26499448, 307489800,3583945822,41930931927,492166822386, 5792986378880,68351501389096,808201629781063, 9574366418412669,113613225065827244, 1350205860499349690,16067869695882894095, 191446722937160655101] |