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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 6 |
| 5 | 144 |
| 6 | 3000 |
| 7 | 64560 |
| 8 | 1498140 |
| 9 | 37906848 |
| 10 | 1046608416 |
| 11 | 31438821600 |
| 12 | 1023129229320 |
| 13 | 35910464987760 |
| 14 | 1353422643322464 |
| 15 | 54548490915316944 |
| 16 | 2342204085734058000 |
| 17 | 106771822456475695680 |
| 18 | 5151207243866077428480 |
| 19 | 262261296920723111462592 |
| 20 | 14053817061169685865626976 |
[1,0,0,0,6,144,3000,64560,1498140,37906848, 1046608416,31438821600,1023129229320, 35910464987760,1353422643322464,54548490915316944, 2342204085734058000,106771822456475695680, 5151207243866077428480,262261296920723111462592, 14053817061169685865626976] |