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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 270 |
| 3 | 7020 |
| 4 | 119340 |
| 5 | 835380 |
| 6 | 4176900 |
| 7 | 242260200 |
| 8 | 888287400 |
| 9 | 32866633800 |
| 10 | 1347531985800 |
| 11 | 4042595957400 |
| 12 | 28298171701800 |
| 13 | 1499803100195400 |
| 14 | 28496258903712600 |
| 15 | 3476543586252937200 |
| 16 | 3476543586252937200 |
| 17 | 26653500827939185200 |
| 18 | 1945705560439560519600 |
| 19 | 1945705560439560519600 |
| 20 | 52534050131868134029200 |
[1,10,270,7020,119340,835380,4176900,242260200, 888287400,32866633800,1347531985800,4042595957400, 28298171701800,1499803100195400,28496258903712600, 3476543586252937200,3476543586252937200, 26653500827939185200,1945705560439560519600, 1945705560439560519600,52534050131868134029200] |