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| n | a(n) |
|---|---|
| 1 | 13 |
| 2 | 180 |
| 3 | 2460 |
| 4 | 10500 |
| 5 | 133560 |
| 6 | 2827440 |
| 7 | 27387360 |
| 8 | 203963760 |
| 9 | 2254412160 |
| 10 | 19260521280 |
| 11 | 233956522800 |
| 12 | 2570029862400 |
| 13 | 33892268810400 |
| 14 | 312098001415200 |
| 15 | 2636529385089600 |
| 16 | 17906040558806400 |
| 17 | 307146357004687200 |
| 18 | 1832625489772677600 |
| 19 | 29247206795963956800 |
| 20 | 387955596028816015200 |
[13,180,2460,10500,133560,2827440,27387360, 203963760,2254412160,19260521280,233956522800, 2570029862400,33892268810400,312098001415200, 2636529385089600,17906040558806400, 307146357004687200,1832625489772677600, 29247206795963956800,387955596028816015200] |