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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 39 |
| 3 | 432 |
| 4 | 6156 |
| 5 | 106920 |
| 6 | 2187000 |
| 7 | 51438240 |
| 8 | 1366787520 |
| 9 | 40474546560 |
| 10 | 1321374902400 |
| 11 | 47140942464000 |
| 12 | 1824354473356800 |
| 13 | 76113765702374400 |
| 14 | 3405263691641011200 |
| 15 | 162618715070203392000 |
| 16 | 8256027072794941440000 |
| 17 | 444024146933226123264000 |
| 18 | 25217509310311152586752000 |
[1,5,39,432,6156,106920,2187000,51438240, 1366787520,40474546560,1321374902400, 47140942464000,1824354473356800,76113765702374400, 3405263691641011200,162618715070203392000, 8256027072794941440000,444024146933226123264000, 25217509310311152586752000] |