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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 27 |
| 4 | 288 |
| 5 | 4500 |
| 6 | 97200 |
| 7 | 2778300 |
| 8 | 101606400 |
| 9 | 4629441600 |
| 10 | 257191200000 |
| 11 | 17116074360000 |
| 12 | 1344389840640000 |
| 13 | 123067686661920000 |
| 14 | 12988374315396480000 |
| 15 | 1565562975516540000000 |
| 16 | 213751531590524928000000 |
| 17 | 32817539834507780352000000 |
[1,4,27,288,4500,97200,2778300,101606400, 4629441600,257191200000,17116074360000, 1344389840640000,123067686661920000, 12988374315396480000,1565562975516540000000, 213751531590524928000000, 32817539834507780352000000] |