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| n | a(n) |
|---|---|
| 7 | 1 |
| 8 | 28 |
| 9 | 462 |
| 10 | 5880 |
| 11 | 63987 |
| 12 | 627396 |
| 13 | 5715424 |
| 14 | 49329280 |
| 15 | 408741333 |
| 16 | 3281882604 |
| 17 | 25708104786 |
| 18 | 197462483400 |
| 19 | 1492924634839 |
| 20 | 11143554045652 |
| 21 | 82310957214948 |
| 22 | 602762379967440 |
| 23 | 4382641999117305 |
| 24 | 31677463851804540 |
| 25 | 227832482998716310 |
| 26 | 1631853797991016600 |
[1,28,462,5880,63987,627396,5715424,49329280, 408741333,3281882604,25708104786,197462483400, 1492924634839,11143554045652,82310957214948, 602762379967440,4382641999117305, 31677463851804540,227832482998716310, 1631853797991016600] |