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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 255 |
| 4 | 4522 |
| 5 | 91896 |
| 6 | 2047452 |
| 7 | 48748986 |
| 8 | 1220457810 |
| 9 | 31779889284 |
| 10 | 854110511124 |
| 11 | 23559266827278 |
| 12 | 664125694509564 |
| 13 | 19070108145820400 |
| 14 | 556345776173277960 |
| 15 | 16455889048642607295 |
| 16 | 492658546882981692690 |
| 17 | 14907686709710614053300 |
| 18 | 455413194094843994648100 |
[1,2,18,255,4522,91896,2047452,48748986, 1220457810,31779889284,854110511124, 23559266827278,664125694509564,19070108145820400, 556345776173277960,16455889048642607295, 492658546882981692690,14907686709710614053300, 455413194094843994648100] |