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| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 49 |
| 8 | 1540 |
| 9 | 39711 |
| 10 | 916895 |
| 11 | 19757815 |
| 12 | 406481544 |
| 13 | 8093990190 |
| 14 | 157366449604 |
| 15 | 3005047770725 |
| 16 | 56594002961496 |
| 17 | 1054285955968882 |
| 18 | 19470069317824125 |
| 19 | 357039166816301200 |
| 20 | 6509613950241656640 |
| 21 | 118118024245256829444 |
[1,49,1540,39711,916895,19757815,406481544, 8093990190,157366449604,3005047770725, 56594002961496,1054285955968882,19470069317824125, 357039166816301200,6509613950241656640, 118118024245256829444] |