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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 15 |
| 2 | 112 |
| 3 | 836 |
| 4 | 6240 |
| 5 | 46576 |
| 6 | 347648 |
| 7 | 2594880 |
| 8 | 19368448 |
| 9 | 144568064 |
| 10 | 1079070720 |
| 11 | 8054293504 |
| 12 | 60118065152 |
| 13 | 448727347200 |
| 14 | 3349346516992 |
| 15 | 24999862747136 |
| 16 | 186601515909120 |
| 17 | 1392812676284416 |
| 18 | 10396095346638848 |
| 19 | 77597512067973120 |
| 20 | 579195715157229568 |
[2,15,112,836,6240,46576,347648,2594880,19368448, 144568064,1079070720,8054293504,60118065152, 448727347200,3349346516992,24999862747136, 186601515909120,1392812676284416, 10396095346638848,77597512067973120, 579195715157229568] |