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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 23 |
| 2 | 109 |
| 3 | 525 |
| 4 | 2543 |
| 5 | 12361 |
| 6 | 60223 |
| 7 | 293899 |
| 8 | 1436105 |
| 9 | 7024405 |
| 10 | 34386235 |
| 11 | 168441635 |
| 12 | 825574805 |
| 13 | 4048257077 |
| 14 | 19858855181 |
| 15 | 97451838245 |
| 16 | 478360096877 |
| 17 | 2348721744139 |
| 18 | 11534669029037 |
| 19 | 56658230250101 |
| 20 | 278351957108055 |
[1,23,109,525,2543,12361,60223,293899,1436105, 7024405,34386235,168441635,825574805,4048257077, 19858855181,97451838245,478360096877, 2348721744139,11534669029037,56658230250101, 278351957108055] |