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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 33 |
| 4 | 252 |
| 5 | 2108 |
| 6 | 18774 |
| 7 | 175045 |
| 8 | 1690260 |
| 9 | 16779012 |
| 10 | 170335360 |
| 11 | 1761496828 |
| 12 | 18501861600 |
| 13 | 196928222832 |
| 14 | 2120156504636 |
| 15 | 23054547056085 |
| 16 | 252901313956980 |
| 17 | 2795875813360980 |
| 18 | 31123866089539440 |
| 19 | 348634514260163164 |
| 20 | 3927223348115402400 |
| 21 | 44464453793202573936 |
| 22 | 505773761881655080800 |
[1,5,33,252,2108,18774,175045,1690260,16779012, 170335360,1761496828,18501861600,196928222832, 2120156504636,23054547056085,252901313956980, 2795875813360980,31123866089539440, 348634514260163164,3927223348115402400, 44464453793202573936,505773761881655080800] |