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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 58 |
| 6 | 333 |
| 7 | 2233 |
| 8 | 17225 |
| 9 | 150104 |
| 10 | 1458150 |
| 11 | 15623032 |
| 12 | 183012659 |
| 13 | 2326875239 |
| 14 | 31911431853 |
| 15 | 469553925838 |
| 16 | 7378704548888 |
| 17 | 123329776031415 |
| 18 | 2184698889699346 |
| 19 | 40885079221516335 |
| 20 | 806020133224179176 |
[1,1,1,3,12,58,333,2233,17225,150104,1458150, 15623032,183012659,2326875239,31911431853, 469553925838,7378704548888,123329776031415, 2184698889699346,40885079221516335, 806020133224179176] |