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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 54 |
| 4 | 542 |
| 5 | 5950 |
| 6 | 69089 |
| 7 | 834807 |
| 8 | 10387628 |
| 9 | 132206325 |
| 10 | 1713016233 |
| 11 | 22520857313 |
| 12 | 299667203315 |
| 13 | 4028078782339 |
| 14 | 54615552455056 |
| 15 | 746073353306341 |
| 16 | 10258385111897258 |
| 17 | 141862903772876529 |
| 18 | 1971827463536643265 |
| 19 | 27532294076219156008 |
| 20 | 386001188585539328720 |
[1,1,6,54,542,5950,69089,834807,10387628, 132206325,1713016233,22520857313,299667203315, 4028078782339,54615552455056,746073353306341, 10258385111897258,141862903772876529, 1971827463536643265,27532294076219156008, 386001188585539328720] |