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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 22 |
| 3 | 246 |
| 4 | 3672 |
| 5 | 68520 |
| 6 | 1534320 |
| 7 | 40083120 |
| 8 | 1196737920 |
| 9 | 40196580480 |
| 10 | 1500156806400 |
| 11 | 61585275628800 |
| 12 | 2758072531737600 |
| 13 | 133812468652262400 |
| 14 | 6991529043750451200 |
| 15 | 391391124208051968000 |
| 16 | 23371064978815217664000 |
[1,3,22,246,3672,68520,1534320,40083120, 1196737920,40196580480,1500156806400, 61585275628800,2758072531737600, 133812468652262400,6991529043750451200, 391391124208051968000,23371064978815217664000] |