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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 135 |
| 6 | 632 |
| 7 | 3194 |
| 8 | 17450 |
| 9 | 101258 |
| 10 | 622694 |
| 11 | 4034892 |
| 12 | 27489676 |
| 13 | 196054798 |
| 14 | 1459552844 |
| 15 | 11297662922 |
| 16 | 90648769970 |
| 17 | 751732064930 |
| 18 | 6429192275568 |
| 19 | 56603447925754 |
| 20 | 512309058662574 |
| 21 | 4761135417168102 |
| 22 | 45389581888641760 |
| 23 | 443470604659923172 |
| 24 | 4436647328514208908 |
[1,1,3,9,33,135,632,3194,17450,101258,622694, 4034892,27489676,196054798,1459552844,11297662922, 90648769970,751732064930,6429192275568, 56603447925754,512309058662574,4761135417168102, 45389581888641760,443470604659923172, 4436647328514208908] |