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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 10 |
| 6 | 39 |
| 7 | 490 |
| 8 | 20631 |
| 9 | 10349290 |
| 10 | 213941840151 |
| 11 | 2214253254659846890 |
| 12 | 473721461633379426414550183191 |
| 13 | 1048939288228833100615882755549676600679754298090 |
[1,1,1,2,3,10,39,490,20631,10349290,213941840151, 2214253254659846890, 473721461633379426414550183191, 1048939288228833100615882755549676600679754298090] |