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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 22 |
| 4 | 174 |
| 5 | 1479 |
| 6 | 16808 |
| 7 | 201834 |
| 8 | 2631594 |
| 9 | 35965555 |
| 10 | 512062566 |
| 11 | 7528425420 |
| 12 | 113708935808 |
| 13 | 1756853846316 |
| 14 | 27676951028496 |
| 15 | 443411345677658 |
| 16 | 7209139541742750 |
| 17 | 118738765611199983 |
| 18 | 1978360119497335826 |
[1,6,22,174,1479,16808,201834,2631594,35965555, 512062566,7528425420,113708935808,1756853846316, 27676951028496,443411345677658,7209139541742750, 118738765611199983,1978360119497335826] |