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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 52 |
| 3 | 632 |
| 4 | 10128 |
| 5 | 202592 |
| 6 | 4862272 |
| 7 | 136143744 |
| 8 | 4356600064 |
| 9 | 156837602816 |
| 10 | 6273504113664 |
| 11 | 276034181003264 |
| 12 | 13249640688160768 |
| 13 | 688981315784368128 |
| 14 | 38582953683924631552 |
| 15 | 2314977221035477925888 |
| 16 | 148158542146270587322368 |
[1,6,52,632,10128,202592,4862272,136143744, 4356600064,156837602816,6273504113664, 276034181003264,13249640688160768, 688981315784368128,38582953683924631552, 2314977221035477925888,148158542146270587322368] |