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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 19 |
| 7 | 50 |
| 8 | 204 |
| 9 | 832 |
| 10 | 4330 |
| 11 | 25227 |
| 12 | 171886 |
| 13 | 1303725 |
| 14 | 10959478 |
| 15 | 100230117 |
| 16 | 989280132 |
| 17 | 10455393155 |
| 18 | 117701173970 |
| 19 | 1405165683359 |
| 20 | 17726785643045 |
| 21 | 235585551038117 |
| 22 | 3289367315407521 |
| 23 | 48136794098893837 |
| 24 | 736721822918719557 |
| 25 | 11768987500655142988 |
[1,0,1,1,3,6,19,50,204,832,4330,25227,171886, 1303725,10959478,100230117,989280132,10455393155, 117701173970,1405165683359,17726785643045, 235585551038117,3289367315407521, 48136794098893837,736721822918719557, 11768987500655142988] |