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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 84 |
| 5 | 480 |
| 6 | 2792 |
| 7 | 16807 |
| 8 | 102900 |
| 9 | 640528 |
| 10 | 4035120 |
| 11 | 25679568 |
| 12 | 164775800 |
| 13 | 1064714400 |
| 14 | 6920635197 |
| 15 | 45214871360 |
| 16 | 296722542900 |
| 17 | 1954878268800 |
| 18 | 12923917122536 |
| 19 | 85705978837392 |
| 20 | 569944757250960 |
| 21 | 3799631728452112 |
| 22 | 25388448354582216 |
| 23 | 169992219503608176 |
[1,3,16,84,480,2792,16807,102900,640528,4035120, 25679568,164775800,1064714400,6920635197, 45214871360,296722542900,1954878268800, 12923917122536,85705978837392,569944757250960, 3799631728452112,25388448354582216, 169992219503608176] |