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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 57 |
| 4 | 1284 |
| 5 | 34220 |
| 6 | 1098720 |
| 7 | 41579328 |
| 8 | 1832244288 |
| 9 | 92830006368 |
| 10 | 5353120671120 |
| 11 | 348383876993900 |
| 12 | 25409389391925264 |
| 13 | 2064511110000765192 |
| 14 | 185885772163424273304 |
| 15 | 18458953746901624026000 |
| 16 | 2012589235930543617012480 |
| 17 | 239897773975844015012351360 |
| 18 | 31132547318002718989156350240 |
| 19 | 4380969784826872849927354999092 |
| 20 | 665896601825393760478978112600400 |
[0,3,57,1284,34220,1098720,41579328,1832244288, 92830006368,5353120671120,348383876993900, 25409389391925264,2064511110000765192, 185885772163424273304,18458953746901624026000, 2012589235930543617012480, 239897773975844015012351360, 31132547318002718989156350240, 4380969784826872849927354999092, 665896601825393760478978112600400] |