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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 57 |
| 4 | 428 |
| 5 | 3172 |
| 6 | 23689 |
| 7 | 176324 |
| 8 | 1312550 |
| 9 | 9757798 |
| 10 | 72480269 |
| 11 | 537854094 |
| 12 | 3987751860 |
| 13 | 29540543908 |
| 14 | 218652961074 |
| 15 | 1617159619805 |
| 16 | 11951595353413 |
| 17 | 88264810625245 |
| 18 | 651404299886762 |
| 19 | 4804261815210433 |
| 20 | 35410065096578748 |
| 21 | 260832137791524693 |
| 22 | 1920169120639498017 |
| 23 | 14127684273966098698 |
[1,1,8,57,428,3172,23689,176324,1312550,9757798, 72480269,537854094,3987751860,29540543908, 218652961074,1617159619805,11951595353413, 88264810625245,651404299886762,4804261815210433, 35410065096578748,260832137791524693, 1920169120639498017,14127684273966098698] |