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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 90 |
| 4 | 1428 |
| 5 | 10600 |
| 6 | 51525 |
| 7 | 190806 |
| 8 | 584080 |
| 9 | 1552608 |
| 10 | 3701025 |
| 11 | 8088850 |
| 12 | 16470036 |
| 13 | 31616520 |
| 14 | 57743413 |
| 15 | 101055150 |
| 16 | 170433600 |
| 17 | 278290816 |
| 18 | 441610785 |
| 19 | 683206218 |
| 20 | 1033218100 |
| 21 | 1530887400 |
| 22 | 2226630021 |
| 23 | 3184447750 |
| 24 | 4484709648 |
| 25 | 6227340000 |
| 26 | 8535450625 |
| 27 | 11559457026 |
| 28 | 15481719540 |
[0,1,90,1428,10600,51525,190806,584080,1552608, 3701025,8088850,16470036,31616520,57743413, 101055150,170433600,278290816,441610785,683206218, 1033218100,1530887400,2226630021,3184447750, 4484709648,6227340000,8535450625,11559457026, 15481719540] |