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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 4 |
| 7 | 20 |
| 8 | 86 |
| 9 | 336 |
| 10 | 1273 |
| 11 | 4880 |
| 12 | 19938 |
| 13 | 90662 |
| 14 | 486753 |
| 15 | 3285964 |
| 16 | 29643278 |
| 17 | 373908194 |
| 18 | 6739368109 |
| 19 | 173801125420 |
| 20 | 6356254132640 |
| 21 | 326203515419552 |
| 22 | 23294352975946580 |
| 23 | 2301176047756537128 |
| 24 | 313285408199163993419 |
| 25 | 58638266023262469408284 |
[0,0,0,0,0,0,4,20,86,336,1273,4880,19938,90662, 486753,3285964,29643278,373908194,6739368109, 173801125420,6356254132640,326203515419552, 23294352975946580,2301176047756537128, 313285408199163993419,58638266023262469408284] |