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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 27 |
| 4 | 280 |
| 5 | 5045 |
| 6 | 134136 |
| 7 | 4269223 |
| 8 | 153188176 |
| 9 | 6657007113 |
| 10 | 371930499280 |
| 11 | 25072409219891 |
| 12 | 1872319689314856 |
| 13 | 154583203638018493 |
| 14 | 14784597239881491400 |
| 15 | 1641532369038107170815 |
| 16 | 201617558936011146124576 |
| 17 | 26755058016106471234608017 |
[1,1,4,27,280,5045,134136,4269223,153188176, 6657007113,371930499280,25072409219891, 1872319689314856,154583203638018493, 14784597239881491400,1641532369038107170815, 201617558936011146124576, 26755058016106471234608017] |