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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 194 |
| 5 | 1970 |
| 6 | 24062 |
| 7 | 343294 |
| 8 | 5601122 |
| 9 | 102847794 |
| 10 | 2098766582 |
| 11 | 47117285270 |
| 12 | 1154031484586 |
| 13 | 30622256174458 |
| 14 | 875092190716382 |
| 15 | 26794239236959806 |
| 16 | 875110094707912562 |
| 17 | 30367988674208286914 |
| 18 | 1115822099409002188358 |
| 19 | 43276913813553367194598 |
| 20 | 1766830322476935945014330 |
[1,1,4,24,194,1970,24062,343294,5601122,102847794, 2098766582,47117285270,1154031484586, 30622256174458,875092190716382,26794239236959806, 875110094707912562,30367988674208286914, 1115822099409002188358,43276913813553367194598, 1766830322476935945014330] |