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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 24 |
| 5 | 157 |
| 6 | 962 |
| 7 | 8575 |
| 8 | 88816 |
| 9 | 948025 |
| 10 | 11551682 |
| 11 | 158525499 |
| 12 | 2329270152 |
| 13 | 37012621141 |
| 14 | 638280394754 |
| 15 | 11767984017847 |
| 16 | 230953513192672 |
| 17 | 4823470878737521 |
| 18 | 106685348433700994 |
| 19 | 2489115873636707187 |
[0,1,2,3,24,157,962,8575,88816,948025,11551682, 158525499,2329270152,37012621141,638280394754, 11767984017847,230953513192672,4823470878737521, 106685348433700994,2489115873636707187] |