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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 54 |
| 4 | 1068 |
| 5 | 8550 |
| 6 | 45873 |
| 7 | 177968 |
| 8 | 562032 |
| 9 | 1519560 |
| 10 | 3662625 |
| 11 | 8057390 |
| 12 | 16477020 |
| 13 | 31712850 |
| 14 | 58018793 |
| 15 | 101639700 |
| 16 | 171525568 |
| 17 | 280160068 |
| 18 | 444636297 |
| 19 | 687881890 |
| 20 | 1040201500 |
| 21 | 1541008350 |
| 22 | 2240952065 |
| 23 | 3204279960 |
| 24 | 4511682288 |
[0,1,54,1068,8550,45873,177968,562032,1519560, 3662625,8057390,16477020,31712850,58018793, 101639700,171525568,280160068,444636297,687881890, 1040201500,1541008350,2240952065,3204279960, 4511682288] |