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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 40 |
| 3 | 285 |
| 4 | 1995 |
| 5 | 13976 |
| 6 | 98665 |
| 7 | 704810 |
| 8 | 5107950 |
| 9 | 37619020 |
| 10 | 281850156 |
| 11 | 2149737335 |
| 12 | 16700012890 |
| 13 | 132177206400 |
| 14 | 1066116496055 |
| 15 | 8764513792396 |
| 16 | 73445461419380 |
| 17 | 627378087294215 |
| 18 | 5462723243482985 |
| 19 | 48480560040789335 |
[1,5,40,285,1995,13976,98665,704810,5107950, 37619020,281850156,2149737335,16700012890, 132177206400,1066116496055,8764513792396, 73445461419380,627378087294215,5462723243482985, 48480560040789335] |