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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 15 |
| 4 | 420 |
| 5 | 63 |
| 6 | 1386 |
| 7 | 9009 |
| 8 | 360360 |
| 9 | 1531530 |
| 10 | 29099070 |
| 11 | 14549535 |
| 12 | 1338557220 |
| 13 | 1673196525 |
| 14 | 10039179150 |
| 15 | 145568097675 |
| 16 | 72201776446800 |
| 17 | 18050444111700 |
| 18 | 9025222055850 |
| 19 | 166966608033225 |
| 20 | 667866432132900 |
| 21 | 6845630929362225 |
[1,6,15,420,63,1386,9009,360360,1531530,29099070, 14549535,1338557220,1673196525,10039179150, 145568097675,72201776446800,18050444111700, 9025222055850,166966608033225,667866432132900, 6845630929362225] |