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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 128 |
| 4 | 11520 |
| 5 | 143360 |
| 6 | 425425 |
| 7 | 2064384 |
| 8 | 619315200 |
| 9 | 280284364800 |
| 10 | 6801567252480 |
| 11 | 27512370460575 |
| 12 | 178541140377600 |
| 13 | 152355106455552000 |
| 14 | 167834385271436083200 |
| 15 | 6074006324109115392000 |
| 16 | 29734853645550994565625 |
| 17 | 231916605102348042240000 |
| 18 | 392866729043377583554560000 |
[1,1,4,128,11520,143360,425425,2064384,619315200, 280284364800,6801567252480,27512370460575, 178541140377600,152355106455552000, 167834385271436083200,6074006324109115392000, 29734853645550994565625,231916605102348042240000, 392866729043377583554560000] |