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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | 40 |
| 4 | 16 |
| 5 | 672 |
| 6 | 576 |
| 7 | 5760 |
| 8 | 57600 |
| 9 | 182784 |
| 10 | 779264 |
| 11 | 3598336 |
| 12 | 10817536 |
| 13 | 41066496 |
| 14 | 8011776 |
| 15 | 616988672 |
| 16 | 1874919424 |
| 17 | 1569325056 |
| 18 | 15693250560 |
| 19 | 19493552128 |
| 20 | 194935521280 |
| 21 | 1949355212800 |
| 22 | 10697459105792 |
| 23 | 36605846880256 |
| 24 | 225320980447232 |
| 25 | 1409990787072 |
[0,2,4,40,16,672,576,5760,57600,182784,779264, 3598336,10817536,41066496,8011776,616988672, 1874919424,1569325056,15693250560,19493552128, 194935521280,1949355212800,10697459105792, 36605846880256,225320980447232,1409990787072] |