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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 85 |
| 4 | 1391 |
| 5 | 27852 |
| 6 | 650161 |
| 7 | 17204220 |
| 8 | 506849175 |
| 9 | 16418826823 |
| 10 | 579491009098 |
| 11 | 22126506842782 |
| 12 | 908765624923517 |
| 13 | 39955891685644210 |
| 14 | 1872870160239756648 |
| 15 | 93252093750481971120 |
| 16 | 4916210973540632697015 |
| 17 | 273627175793531458018185 |
| 18 | 16036039197194394497206285 |
| 19 | 987180880355901292395754555 |
| 20 | 63693966375385851829434069094 |
[1,1,7,85,1391,27852,650161,17204220,506849175, 16418826823,579491009098,22126506842782, 908765624923517,39955891685644210, 1872870160239756648,93252093750481971120, 4916210973540632697015,273627175793531458018185, 16036039197194394497206285, 987180880355901292395754555, 63693966375385851829434069094] |