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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 25 |
| 4 | 149 |
| 5 | 1081 |
| 6 | 9365 |
| 7 | 94585 |
| 8 | 1091669 |
| 9 | 14174521 |
| 10 | 204495125 |
| 11 | 3245265145 |
| 12 | 56183135189 |
| 13 | 1053716696761 |
| 14 | 21282685940885 |
| 15 | 460566381955705 |
| 16 | 10631309363962709 |
| 17 | 260741534058271801 |
| 18 | 6771069326513690645 |
[0,1,5,25,149,1081,9365,94585,1091669,14174521, 204495125,3245265145,56183135189,1053716696761, 21282685940885,460566381955705,10631309363962709, 260741534058271801,6771069326513690645] |