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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 36 |
| 3 | 240 |
| 4 | 1344 |
| 5 | 6912 |
| 6 | 33792 |
| 7 | 159744 |
| 8 | 737280 |
| 9 | 3342336 |
| 10 | 14942208 |
| 11 | 66060288 |
| 12 | 289406976 |
| 13 | 1258291200 |
| 14 | 5435817984 |
| 15 | 23353884672 |
| 16 | 99857989632 |
| 17 | 425201762304 |
| 18 | 1803886264320 |
| 19 | 7627861917696 |
| 20 | 32160715112448 |
| 21 | 135239930216448 |
[3,36,240,1344,6912,33792,159744,737280,3342336, 14942208,66060288,289406976,1258291200,5435817984, 23353884672,99857989632,425201762304, 1803886264320,7627861917696,32160715112448, 135239930216448] |