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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 60 |
| 5 | 326 |
| 6 | 2065 |
| 7 | 14508 |
| 8 | 116845 |
| 9 | 1039459 |
| 10 | 10339365 |
| 11 | 112376487 |
| 12 | 1339665295 |
| 13 | 17256611005 |
| 14 | 240193792120 |
| 15 | 3578746993871 |
| 16 | 56986570945387 |
| 17 | 963868021665359 |
| 18 | 17281651020455445 |
| 19 | 327058650473873893 |
| 20 | 6519981694119182165 |
| 21 | 136489249161324882063 |
[1,1,3,13,60,326,2065,14508,116845,1039459, 10339365,112376487,1339665295,17256611005, 240193792120,3578746993871,56986570945387, 963868021665359,17281651020455445, 327058650473873893,6519981694119182165, 136489249161324882063] |