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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 28 |
| 5 | 134 |
| 6 | 729 |
| 7 | 4408 |
| 8 | 29256 |
| 9 | 210710 |
| 10 | 1633107 |
| 11 | 13528646 |
| 12 | 119117240 |
| 13 | 1109528752 |
| 14 | 10889570768 |
| 15 | 112226155225 |
| 16 | 1210829041710 |
| 17 | 13640416024410 |
| 18 | 160069458445202 |
| 19 | 1952602490538038 |
| 20 | 24712910192430620 |
| 21 | 323964329622503527 |
| 22 | 4391974577299578248 |
| 23 | 61488854148194151940 |
[1,1,2,7,28,134,729,4408,29256,210710,1633107, 13528646,119117240,1109528752,10889570768, 112226155225,1210829041710,13640416024410, 160069458445202,1952602490538038, 24712910192430620,323964329622503527, 4391974577299578248,61488854148194151940] |