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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 240 |
| 4 | 12400 |
| 5 | 1242720 |
| 6 | 202721064 |
| 7 | 48537596352 |
| 8 | 15957585674496 |
| 9 | 6876698410667520 |
| 10 | 3753254881686618880 |
| 11 | 2526792466623639379968 |
| 12 | 2054649298830229608019968 |
| 13 | 1983702201237461333545885696 |
[1,2,12,240,12400,1242720,202721064,48537596352, 15957585674496,6876698410667520, 3753254881686618880,2526792466623639379968, 2054649298830229608019968, 1983702201237461333545885696] |