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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 30 |
| 3 | 150 |
| 4 | 750 |
| 5 | 3750 |
| 6 | 18750 |
| 7 | 93750 |
| 8 | 468750 |
| 9 | 2343735 |
| 10 | 11718600 |
| 11 | 58592640 |
| 12 | 292961400 |
| 13 | 1464798000 |
| 14 | 7323945000 |
| 15 | 36619500000 |
| 16 | 183096375000 |
| 17 | 915476250000 |
| 18 | 4577353125210 |
| 19 | 22886625003000 |
| 20 | 114432421904040 |
| 21 | 572158593987000 |
[1,6,30,150,750,3750,18750,93750,468750,2343735, 11718600,58592640,292961400,1464798000,7323945000, 36619500000,183096375000,915476250000, 4577353125210,22886625003000,114432421904040, 572158593987000] |