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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 60 |
| 4 | 1000 |
| 5 | 19970 |
| 6 | 448160 |
| 7 | 10926360 |
| 8 | 283651245 |
| 9 | 7740058300 |
| 10 | 220046970860 |
| 11 | 6476695275680 |
| 12 | 196438030797880 |
| 13 | 6117627849485360 |
| 14 | 195082685133612800 |
| 15 | 6355848358118392400 |
| 16 | 211189970909192038500 |
| 17 | 7146354688384980282000 |
| 18 | 245970478274041025623200 |
| 19 | 8602606263466490521359400 |
| 20 | 305460999044315834902424200 |
| 21 | 11003870605124169641012461600 |
[1,5,60,1000,19970,448160,10926360,283651245, 7740058300,220046970860,6476695275680, 196438030797880,6117627849485360, 195082685133612800,6355848358118392400, 211189970909192038500,7146354688384980282000, 245970478274041025623200, 8602606263466490521359400, 305460999044315834902424200, 11003870605124169641012461600] |