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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 100 |
| 3 | 4464 |
| 4 | 286816 |
| 5 | 24053120 |
| 6 | 2488967136 |
| 7 | 306383969920 |
| 8 | 43726697867008 |
| 9 | 7098711727021056 |
| 10 | 1291743506952832000 |
| 11 | 260410631081389420544 |
| 12 | 57609344863582419640320 |
| 13 | 13875489289115958335143936 |
| 14 | 3614364399291754755286614016 |
| 15 | 1012444950785630853817442304000 |
| 16 | 303479487751656117544078504493056 |
| 17 | 96925825525767333731669511270563840 |
| 18 | 32859305845564004294368688506268024832 |
| 19 | 11784943093649049136596829229809817092096 |
| 20 | 4458038385946160559288726139220234076160000 |
| 21 | 1773928724624151210275576625473634276174987264 |
| 22 | 740706616375525604793089813921394696991733186560 |
[1,4,100,4464,286816,24053120,2488967136, 306383969920,43726697867008,7098711727021056, 1291743506952832000,260410631081389420544, 57609344863582419640320, 13875489289115958335143936, 3614364399291754755286614016, 1012444950785630853817442304000, 303479487751656117544078504493056, 96925825525767333731669511270563840, 32859305845564004294368688506268024832, 11784943093649049136596829229809817092096, 4458038385946160559288726139220234076160000, 1773928724624151210275576625473634276174987264, 740706616375525604793089813921394696991733186560] |