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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 56 |
| 4 | 1810 |
| 5 | 206252 |
| 6 | 86874564 |
| 7 | 132282417920 |
| 8 | 770670360699138 |
| 9 | 16425660314368351892 |
| 10 | 1367610300690018553312276 |
| 11 | 419460465362069257397304825200 |
| 12 | 509571049488109525160616367158261124 |
| 13 | 2290638298071684282149128235413262383804352 |
[1,2,6,56,1810,206252,86874564,132282417920, 770670360699138,16425660314368351892, 1367610300690018553312276, 419460465362069257397304825200, 509571049488109525160616367158261124, 2290638298071684282149128235413262383804352] |