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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 40 |
| 3 | 1260 |
| 4 | 72576 |
| 5 | 6652800 |
| 6 | 889574400 |
| 7 | 163459296000 |
| 8 | 39520825344000 |
| 9 | 12164510040883200 |
| 10 | 4644631106519040000 |
| 11 | 2154334728240414720000 |
| 12 | 1193170003333152768000000 |
| 13 | 777776389315596582912000000 |
| 14 | 589450799582646796969574400000 |
| 15 | 513927415886120176107847680000000 |
[1,3,40,1260,72576,6652800,889574400,163459296000, 39520825344000,12164510040883200, 4644631106519040000,2154334728240414720000, 1193170003333152768000000, 777776389315596582912000000, 589450799582646796969574400000, 513927415886120176107847680000000] |