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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 70 |
| 6 | 331 |
| 7 | 1863 |
| 8 | 11637 |
| 9 | 81110 |
| 10 | 635550 |
| 11 | 5495339 |
| 12 | 51590494 |
| 13 | 524043395 |
| 14 | 5743546943 |
| 15 | 67478821537 |
| 16 | 844983073638 |
| 17 | 11240221721390 |
| 18 | 158365579448315 |
| 19 | 2355375055596386 |
| 20 | 36870671943986643 |
| 21 | 606008531691619131 |
| 22 | 10435226671431973345 |
| 23 | 187860338952519968538 |
[1,1,2,6,19,70,331,1863,11637,81110,635550, 5495339,51590494,524043395,5743546943,67478821537, 844983073638,11240221721390,158365579448315, 2355375055596386,36870671943986643, 606008531691619131,10435226671431973345, 187860338952519968538] |