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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 25 |
| 5 | 61 |
| 6 | 481 |
| 7 | 2731 |
| 8 | 10417 |
| 9 | 91225 |
| 10 | 681121 |
| 11 | 3493711 |
| 12 | 33597961 |
| 13 | 303321877 |
| 14 | 1938378625 |
| 15 | 20282865331 |
| 16 | 211375647841 |
| 17 | 1607008257841 |
| 18 | 18157826367937 |
| 19 | 212200671085975 |
| 20 | 1860991143630841 |
| 21 | 22560913203079021 |
| 22 | 289933758771407521 |
| 23 | 2869267483843753147 |
| 24 | 37116733726117707025 |
[1,1,1,7,25,61,481,2731,10417,91225,681121, 3493711,33597961,303321877,1938378625,20282865331, 211375647841,1607008257841,18157826367937, 212200671085975,1860991143630841, 22560913203079021,289933758771407521, 2869267483843753147,37116733726117707025] |