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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 9 |
| 5 | 96 |
| 6 | 145 |
| 7 | 4320 |
| 8 | 11025 |
| 9 | 179200 |
| 10 | 693441 |
| 11 | 36288000 |
| 12 | 62610625 |
| 13 | 5748019200 |
| 14 | 15259154625 |
| 15 | 378002200576 |
| 16 | 4108830350625 |
| 17 | 334764638208000 |
| 18 | 643373556450625 |
| 19 | 115242726703104000 |
| 20 | 309281197713168681 |
| 21 | 14870534508544000000 |
| 22 | 168541849294187630625 |
[1,1,1,4,9,96,145,4320,11025,179200,693441, 36288000,62610625,5748019200,15259154625, 378002200576,4108830350625,334764638208000, 643373556450625,115242726703104000, 309281197713168681,14870534508544000000, 168541849294187630625] |