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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 140 |
| 3 | 2310 |
| 4 | 42042 |
| 5 | 816816 |
| 6 | 16628040 |
| 7 | 350574510 |
| 8 | 7595781050 |
| 9 | 168212023980 |
| 10 | 3792416540640 |
| 11 | 86787993910800 |
| 12 | 2011383287449200 |
| 13 | 47123837020238400 |
| 14 | 1114478745528638160 |
| 15 | 26575401262863040830 |
| 16 | 638330716607984804250 |
| 17 | 15431925043610580004500 |
| 18 | 375239440534109892741000 |
[1,10,140,2310,42042,816816,16628040,350574510, 7595781050,168212023980,3792416540640, 86787993910800,2011383287449200,47123837020238400, 1114478745528638160,26575401262863040830, 638330716607984804250,15431925043610580004500, 375239440534109892741000] |