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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 36 |
| 4 | 304 |
| 5 | 2808 |
| 6 | 27475 |
| 7 | 279845 |
| 8 | 2935987 |
| 9 | 31511097 |
| 10 | 344344868 |
| 11 | 3818320487 |
| 12 | 42855633210 |
| 13 | 485923475563 |
| 14 | 5557803724920 |
| 15 | 64046876264292 |
| 16 | 742908320701832 |
| 17 | 8667090253409215 |
| 18 | 101631581618367133 |
| 19 | 1197190915359577973 |
| 20 | 14160413911721178800 |
[1,1,5,36,304,2808,27475,279845,2935987,31511097, 344344868,3818320487,42855633210,485923475563, 5557803724920,64046876264292,742908320701832, 8667090253409215,101631581618367133, 1197190915359577973,14160413911721178800] |