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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 46 |
| 5 | 343 |
| 6 | 3025 |
| 7 | 32811 |
| 8 | 417348 |
| 9 | 6106921 |
| 10 | 102307571 |
| 11 | 1918139824 |
| 12 | 40190540565 |
| 13 | 928661958828 |
| 14 | 23551552524966 |
| 15 | 651213150740841 |
| 16 | 19523328447786346 |
| 17 | 631923020784069573 |
| 18 | 21984209405892842663 |
| 19 | 819109566359501449734 |
| 20 | 32576039720255480451008 |
| 21 | 1378639634715738629523321 |
[1,1,2,9,46,343,3025,32811,417348,6106921, 102307571,1918139824,40190540565,928661958828, 23551552524966,651213150740841,19523328447786346, 631923020784069573,21984209405892842663, 819109566359501449734,32576039720255480451008, 1378639634715738629523321] |