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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 36 |
| 3 | 370 |
| 4 | 4012 |
| 5 | 44814 |
| 6 | 510198 |
| 7 | 5886206 |
| 8 | 68579020 |
| 9 | 805045276 |
| 10 | 9507007686 |
| 11 | 112817021332 |
| 12 | 1344160003030 |
| 13 | 16069300956726 |
| 14 | 192662610805386 |
| 15 | 2315694030560640 |
| 16 | 27893938099222316 |
| 17 | 336643301659031102 |
| 18 | 4069747367955175236 |
| 19 | 49274614400855690158 |
[1,4,36,370,4012,44814,510198,5886206,68579020, 805045276,9507007686,112817021332,1344160003030, 16069300956726,192662610805386,2315694030560640, 27893938099222316,336643301659031102, 4069747367955175236,49274614400855690158] |