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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 50 |
| 4 | 705 |
| 5 | 12225 |
| 6 | 244076 |
| 7 | 5408850 |
| 8 | 130087875 |
| 9 | 3345893240 |
| 10 | 91094645450 |
| 11 | 2606026116783 |
| 12 | 77908655011205 |
| 13 | 2423758771361300 |
| 14 | 78209895085897845 |
| 15 | 2610730390260224350 |
| 16 | 89962745874096081282 |
| 17 | 3194452580744306873560 |
| 18 | 116712765368638543260825 |
[1,1,5,50,705,12225,244076,5408850,130087875, 3345893240,91094645450,2606026116783, 77908655011205,2423758771361300,78209895085897845, 2610730390260224350,89962745874096081282, 3194452580744306873560,116712765368638543260825] |