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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 104 |
| 4 | 4196 |
| 5 | 225216 |
| 6 | 14845072 |
| 7 | 1151255440 |
| 8 | 102289538128 |
| 9 | 10226417550096 |
| 10 | 1135388485042624 |
| 11 | 138583671424928128 |
| 12 | 18446474604149746176 |
| 13 | 2659732597343823233280 |
| 14 | 413060592233577210697984 |
| 15 | 68754628660531280009195776 |
| 16 | 12213125156726936259944672320 |
| 17 | 2306358043375070604869802287616 |
| 18 | 461443265563759624969778550969344 |
| 19 | 97514484569091438266511351355560448 |
[1,1,4,104,4196,225216,14845072,1151255440, 102289538128,10226417550096,1135388485042624, 138583671424928128,18446474604149746176, 2659732597343823233280,413060592233577210697984, 68754628660531280009195776, 12213125156726936259944672320, 2306358043375070604869802287616, 461443265563759624969778550969344, 97514484569091438266511351355560448] |