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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 33 |
| 4 | 148 |
| 5 | 765 |
| 6 | 4626 |
| 7 | 32431 |
| 8 | 259512 |
| 9 | 2335689 |
| 10 | 23356990 |
| 11 | 256927011 |
| 12 | 3083124276 |
| 13 | 40080615757 |
| 14 | 561128620794 |
| 15 | 8416929312135 |
| 16 | 134670868994416 |
| 17 | 2289404772905361 |
| 18 | 41209285912296822 |
| 19 | 782976432333639979 |
| 20 | 15659528646672799980 |
| 21 | 328850101580128800021 |
[1,2,8,33,148,765,4626,32431,259512,2335689, 23356990,256927011,3083124276,40080615757, 561128620794,8416929312135,134670868994416, 2289404772905361,41209285912296822, 782976432333639979,15659528646672799980, 328850101580128800021] |