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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 66 |
| 5 | 772 |
| 6 | 6760 |
| 7 | 60122 |
| 8 | 552930 |
| 9 | 4887052 |
| 10 | 42365416 |
| 11 | 361418592 |
| 12 | 3063883318 |
| 13 | 25819450218 |
| 14 | 215875963118 |
| 15 | 1793852851690 |
| 16 | 14833014554258 |
| 17 | 122147248758898 |
| 18 | 1002084660185318 |
| 19 | 8192705916505028 |
| 20 | 66777880125812344 |
| 21 | 542833111487459532 |
| 22 | 4401913323626254612 |
| 23 | 35616479684643020150 |
[0,0,0,6,66,772,6760,60122,552930,4887052, 42365416,361418592,3063883318,25819450218, 215875963118,1793852851690,14833014554258, 122147248758898,1002084660185318,8192705916505028, 66777880125812344,542833111487459532, 4401913323626254612,35616479684643020150] |