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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 16 |
| 3 | 212 |
| 4 | 3320 |
| 5 | 57024 |
| 6 | 1038928 |
| 7 | 19718512 |
| 8 | 385668448 |
| 9 | 7718866880 |
| 10 | 157326086656 |
| 11 | 3254310606208 |
| 12 | 68142850580480 |
| 13 | 1441588339943168 |
| 14 | 30765576147680000 |
| 15 | 661561298256228096 |
| 16 | 14319744815795062272 |
| 17 | 311756656998135770112 |
| 18 | 6822215641015820419072 |
[1,2,16,212,3320,57024,1038928,19718512,385668448, 7718866880,157326086656,3254310606208, 68142850580480,1441588339943168,30765576147680000, 661561298256228096,14319744815795062272, 311756656998135770112,6822215641015820419072] |