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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 92 |
| 4 | 752 |
| 5 | 6352 |
| 6 | 54768 |
| 7 | 478928 |
| 8 | 4231424 |
| 9 | 37680320 |
| 10 | 337622912 |
| 11 | 3040354176 |
| 12 | 27492359936 |
| 13 | 249463806464 |
| 14 | 2270319909632 |
| 15 | 20714443816192 |
| 16 | 189418898063360 |
| 17 | 1735482632719360 |
| 18 | 15928224355854336 |
| 19 | 146414296847992832 |
| 20 | 1347721096376573952 |
| 21 | 12421053168197722112 |
[1,2,12,92,752,6352,54768,478928,4231424,37680320, 337622912,3040354176,27492359936,249463806464, 2270319909632,20714443816192,189418898063360, 1735482632719360,15928224355854336, 146414296847992832,1347721096376573952, 12421053168197722112] |