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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 67 |
| 5 | 405 |
| 6 | 2839 |
| 7 | 22717 |
| 8 | 204459 |
| 9 | 2044597 |
| 10 | 22490575 |
| 11 | 269886909 |
| 12 | 3508529827 |
| 13 | 49119417589 |
| 14 | 736791263847 |
| 15 | 11788660221565 |
| 16 | 200407223766619 |
| 17 | 3607330027799157 |
| 18 | 68539270528183999 |
| 19 | 1370785410563679997 |
| 20 | 28786493621837279955 |
| 21 | 633302859680420159029 |
| 22 | 14565965772649663657687 |
[1,1,3,13,67,405,2839,22717,204459,2044597, 22490575,269886909,3508529827,49119417589, 736791263847,11788660221565,200407223766619, 3607330027799157,68539270528183999, 1370785410563679997,28786493621837279955, 633302859680420159029,14565965772649663657687] |