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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 25 |
| 3 | 150 |
| 4 | 1050 |
| 5 | 9450 |
| 6 | 113400 |
| 7 | 1927800 |
| 8 | 48195000 |
| 9 | 1831410000 |
| 10 | 108053190000 |
| 11 | 10048946670000 |
| 12 | 1487244107160000 |
| 13 | 352476853396920000 |
| 14 | 134293681144226520000 |
| 15 | 82456320222555083280000 |
| 16 | 81714213340552087530480000 |
| 17 | 130824455558223892136298480000 |
[1,5,25,150,1050,9450,113400,1927800,48195000, 1831410000,108053190000,10048946670000, 1487244107160000,352476853396920000, 134293681144226520000,82456320222555083280000, 81714213340552087530480000, 130824455558223892136298480000] |