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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 4 |
| 2 | 40 |
| 3 | 228 |
| 4 | 960 |
| 5 | 3200 |
| 6 | 8904 |
| 7 | 21560 |
| 8 | 46848 |
| 9 | 93420 |
| 10 | 173800 |
| 11 | 305404 |
| 12 | 511680 |
| 13 | 823368 |
| 14 | 1279880 |
| 15 | 1930800 |
| 16 | 2837504 |
| 17 | 4074900 |
| 18 | 5733288 |
| 19 | 7920340 |
| 20 | 10763200 |
| 21 | 14410704 |
| 22 | 19035720 |
| 23 | 24837608 |
| 24 | 32044800 |
| 25 | 40917500 |
| 26 | 51750504 |
| 27 | 64876140 |
| 28 | 80667328 |
| 29 | 99540760 |
| 30 | 121960200 |
[0,4,40,228,960,3200,8904,21560,46848,93420, 173800,305404,511680,823368,1279880,1930800, 2837504,4074900,5733288,7920340,10763200,14410704, 19035720,24837608,32044800,40917500,51750504, 64876140,80667328,99540760,121960200] |