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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 26 |
| 6 | 261 |
| 7 | 3216 |
| 8 | 19617 |
| 9 | 80860 |
| 10 | 262651 |
| 11 | 737716 |
| 12 | 1920821 |
| 13 | 5013152 |
| 14 | 14277485 |
| 15 | 47610876 |
| 16 | 186355041 |
| 17 | 820625616 |
| 18 | 3869589607 |
| 19 | 19039193980 |
| 20 | 96332399701 |
| 21 | 499138921736 |
| 22 | 2639262062801 |
| 23 | 14234781051932 |
| 24 | 78188865206145 |
| 25 | 437305612997376 |
| 26 | 2487692697142251 |
[1,1,1,2,5,26,261,3216,19617,80860,262651,737716, 1920821,5013152,14277485,47610876,186355041, 820625616,3869589607,19039193980,96332399701, 499138921736,2639262062801,14234781051932, 78188865206145,437305612997376,2487692697142251] |