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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 8 |
| 3 | 53 |
| 4 | 316 |
| 5 | 1785 |
| 6 | 9744 |
| 7 | 51997 |
| 8 | 273092 |
| 9 | 1417889 |
| 10 | 7299160 |
| 11 | 37334661 |
| 12 | 190028748 |
| 13 | 963565513 |
| 14 | 4871514656 |
| 15 | 24572321645 |
| 16 | 123720601684 |
| 17 | 622038982257 |
| 18 | 3123938806632 |
| 19 | 15674669614549 |
| 20 | 78593250398300 |
| 21 | 393845861293721 |
[0,1,8,53,316,1785,9744,51997,273092,1417889, 7299160,37334661,190028748,963565513,4871514656, 24572321645,123720601684,622038982257, 3123938806632,15674669614549,78593250398300, 393845861293721] |