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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 48 |
| 3 | 972 |
| 4 | 7680 |
| 5 | 37500 |
| 6 | 136080 |
| 7 | 403368 |
| 8 | 1032192 |
| 9 | 2361960 |
| 10 | 4950000 |
| 11 | 9663060 |
| 12 | 17791488 |
| 13 | 31188612 |
| 14 | 52437840 |
| 15 | 85050000 |
| 16 | 133693440 |
| 17 | 204459408 |
| 18 | 305165232 |
| 19 | 445697820 |
| 20 | 638400000 |
| 21 | 898502220 |
| 22 | 1244602128 |
| 23 | 1699194552 |
| 24 | 2289254400 |
| 25 | 3046875000 |
| 26 | 4009964400 |
| 27 | 5223002148 |
[0,48,972,7680,37500,136080,403368,1032192, 2361960,4950000,9663060,17791488,31188612, 52437840,85050000,133693440,204459408,305165232, 445697820,638400000,898502220,1244602128, 1699194552,2289254400,3046875000,4009964400, 5223002148] |