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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | 302 |
| 4 | 8104 |
| 5 | 947642 |
| 6 | 86855404 |
| 7 | 16203909542 |
| 8 | 3130092938704 |
| 9 | 896924477276402 |
| 10 | 290713861720990804 |
| 11 | 121467176505314129822 |
| 12 | 58492863120535523766904 |
| 13 | 33925794100542844193202602 |
[0,2,4,302,8104,947642,86855404,16203909542, 3130092938704,896924477276402,290713861720990804, 121467176505314129822,58492863120535523766904, 33925794100542844193202602] |