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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 24 |
| 4 | 720 |
| 5 | 151200 |
| 6 | 302400 |
| 7 | 1814400 |
| 8 | 4191264000 |
| 9 | 8382528000 |
| 10 | 251727315840000 |
| 11 | 503454631680000 |
| 12 | 3020727790080000 |
| 13 | 1542111744113740800000 |
| 14 | 3084223488227481600000 |
| 15 | 92526704646824448000000 |
| 16 | 555160227880946688000000 |
| 17 | 1110320455761893376000000 |
| 18 | 10769764221549079560253440000000 |
[1,2,12,24,720,151200,302400,1814400,4191264000, 8382528000,251727315840000,503454631680000, 3020727790080000,1542111744113740800000, 3084223488227481600000,92526704646824448000000, 555160227880946688000000, 1110320455761893376000000, 10769764221549079560253440000000] |