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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 17 |
| 4 | 105 |
| 5 | 481 |
| 6 | 3261 |
| 7 | 16801 |
| 8 | 119697 |
| 9 | 656129 |
| 10 | 4819061 |
| 11 | 27447601 |
| 12 | 205776121 |
| 13 | 1202943457 |
| 14 | 9152680109 |
| 15 | 54524185409 |
| 16 | 419491297313 |
| 17 | 2534963932417 |
| 18 | 19673179986661 |
| 19 | 120224135048273 |
| 20 | 939543098579081 |
| 21 | 5793676726569697 |
[1,1,5,17,105,481,3261,16801,119697,656129, 4819061,27447601,205776121,1202943457,9152680109, 54524185409,419491297313,2534963932417, 19673179986661,120224135048273,939543098579081, 5793676726569697] |