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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 17 |
| 4 | 83 |
| 5 | 639 |
| 6 | 5749 |
| 7 | 53227 |
| 8 | 561273 |
| 9 | 7216577 |
| 10 | 94292531 |
| 11 | 1352253561 |
| 12 | 21657812923 |
| 13 | 359338829407 |
| 14 | 6460367397093 |
| 15 | 126124578755939 |
| 16 | 2527688612931569 |
| 17 | 54137820027005697 |
| 18 | 1236730462664172643 |
| 19 | 29137619131277727457 |
| 20 | 725282418459957414051 |
| 21 | 18981526480933601454911 |
[1,1,3,17,83,639,5749,53227,561273,7216577, 94292531,1352253561,21657812923,359338829407, 6460367397093,126124578755939,2527688612931569, 54137820027005697,1236730462664172643, 29137619131277727457,725282418459957414051, 18981526480933601454911] |