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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 40 |
| 4 | 240 |
| 5 | 1280 |
| 6 | 6400 |
| 7 | 30720 |
| 8 | 143360 |
| 9 | 655360 |
| 10 | 2949120 |
| 11 | 13107200 |
| 12 | 57671680 |
| 13 | 251658240 |
| 14 | 1090519040 |
| 15 | 4697620480 |
| 16 | 20132659200 |
| 17 | 85899345920 |
| 18 | 365072220160 |
| 19 | 1546188226560 |
| 20 | 6528350289920 |
| 21 | 27487790694400 |
| 22 | 115448720916480 |
[0,5,40,240,1280,6400,30720,143360,655360,2949120, 13107200,57671680,251658240,1090519040,4697620480, 20132659200,85899345920,365072220160, 1546188226560,6528350289920,27487790694400, 115448720916480] |