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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 79 |
| 5 | 631 |
| 6 | 6171 |
| 7 | 70974 |
| 8 | 934493 |
| 9 | 13812955 |
| 10 | 225892738 |
| 11 | 4041653903 |
| 12 | 78416804094 |
| 13 | 1638071535998 |
| 14 | 36622481352509 |
| 15 | 871920455890863 |
| 16 | 22011856296991521 |
| 17 | 587044908015897519 |
| 18 | 16485592791887247448 |
[1,1,3,13,79,631,6171,70974,934493,13812955, 225892738,4041653903,78416804094,1638071535998, 36622481352509,871920455890863,22011856296991521, 587044908015897519,16485592791887247448] |