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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 10 |
| 3 | 72 |
| 4 | 664 |
| 5 | 5376 |
| 6 | 47968 |
| 7 | 406400 |
| 8 | 3585408 |
| 9 | 30987264 |
| 10 | 272565760 |
| 11 | 2378450944 |
| 12 | 20921604096 |
| 13 | 183506403328 |
| 14 | 1615798558720 |
| 15 | 14215745994752 |
| 16 | 125323120574464 |
| 17 | 1104802314190848 |
| 18 | 9750937675890688 |
| 19 | 86084069811027968 |
| 20 | 760548158573379584 |
[1,10,72,664,5376,47968,406400,3585408,30987264, 272565760,2378450944,20921604096,183506403328, 1615798558720,14215745994752,125323120574464, 1104802314190848,9750937675890688, 86084069811027968,760548158573379584] |