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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 3 |
| 6 | 8 |
| 7 | 30 |
| 8 | 222 |
| 9 | 1302 |
| 10 | 8442 |
| 11 | 63570 |
| 12 | 545473 |
| 13 | 5249163 |
| 14 | 55941128 |
| 15 | 653682990 |
| 16 | 8597126190 |
| 17 | 117809490990 |
| 18 | 1730350233390 |
| 19 | 27183297753390 |
| 20 | 454752069221550 |
| 21 | 8070074352360750 |
| 22 | 151403473011001710 |
| 23 | 2993918729983972590 |
| 24 | 62232717584055513822 |
| 25 | 1356493891878893498262 |
[0,0,0,1,3,8,30,222,1302,8442,63570,545473, 5249163,55941128,653682990,8597126190, 117809490990,1730350233390,27183297753390, 454752069221550,8070074352360750, 151403473011001710,2993918729983972590, 62232717584055513822,1356493891878893498262] |