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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 23 |
| 3 | 374 |
| 4 | 7095 |
| 5 | 146916 |
| 6 | 3219216 |
| 7 | 73386170 |
| 8 | 1722567143 |
| 9 | 41352865400 |
| 10 | 1010607195741 |
| 11 | 25058477434562 |
| 12 | 628845572227600 |
| 13 | 15941429819185752 |
| 14 | 407626109449551300 |
| 15 | 10501154649486399096 |
| 16 | 272294680440574235015 |
| 17 | 7101160966497659412010 |
| 18 | 186134223613500403098396 |
[1,2,23,374,7095,146916,3219216,73386170, 1722567143,41352865400,1010607195741, 25058477434562,628845572227600,15941429819185752, 407626109449551300,10501154649486399096, 272294680440574235015,7101160966497659412010, 186134223613500403098396] |