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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 27 |
| 6 | 112 |
| 7 | 453 |
| 8 | 2137 |
| 9 | 10691 |
| 10 | 58435 |
| 11 | 340187 |
| 12 | 2110016 |
| 13 | 13829358 |
| 14 | 95474679 |
| 15 | 691538954 |
| 16 | 5240280999 |
| 17 | 41432965441 |
| 18 | 341040295916 |
| 19 | 2916376121375 |
| 20 | 25862097370783 |
| 21 | 237434958512487 |
| 22 | 2253358056604465 |
| 23 | 22076003464423853 |
| 24 | 222979436686398848 |
| 25 | 2319295172150784296 |
[0,1,2,9,27,112,453,2137,10691,58435,340187, 2110016,13829358,95474679,691538954,5240280999, 41432965441,341040295916,2916376121375, 25862097370783,237434958512487,2253358056604465, 22076003464423853,222979436686398848, 2319295172150784296] |