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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 128 |
| 5 | 600 |
| 6 | 2688 |
| 7 | 7350 |
| 8 | 19968 |
| 9 | 42336 |
| 10 | 89600 |
| 11 | 163350 |
| 12 | 297600 |
| 13 | 490776 |
| 14 | 809088 |
| 15 | 1242150 |
| 16 | 1906688 |
| 17 | 2774400 |
| 18 | 4036608 |
| 19 | 5633766 |
| 20 | 7862400 |
| 21 | 10613400 |
| 22 | 14326400 |
| 23 | 18818646 |
| 24 | 24718848 |
| 25 | 31740000 |
[0,0,6,128,600,2688,7350,19968,42336,89600,163350, 297600,490776,809088,1242150,1906688,2774400, 4036608,5633766,7862400,10613400,14326400, 18818646,24718848,31740000] |