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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 45 |
| 4 | 820 |
| 5 | 19820 |
| 6 | 582007 |
| 7 | 19812744 |
| 8 | 760177656 |
| 9 | 32275309743 |
| 10 | 1497313010037 |
| 11 | 75208566398988 |
| 12 | 4062020902196139 |
| 13 | 234638046113989856 |
| 14 | 14432573619909530980 |
| 15 | 941883830760366274935 |
| 16 | 65013065172020161949992 |
| 17 | 4733236746727327140204578 |
| 18 | 362575149419405494321544263 |
[1,1,4,45,820,19820,582007,19812744,760177656, 32275309743,1497313010037,75208566398988, 4062020902196139,234638046113989856, 14432573619909530980,941883830760366274935, 65013065172020161949992,4733236746727327140204578, 362575149419405494321544263] |